/* * alloc.c * Copyright (C) 2000-2003 Michel Lespinasse * Copyright (C) 1999-2000 Aaron Holtzman * * This file is part of mpeg2dec, a free MPEG-2 video stream decoder. * See http://libmpeg2.sourceforge.net/ for updates. * * mpeg2dec is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * mpeg2dec is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA * * $Id$ * libmpeg2 sync history: * 2008-07-01 - CVS revision 1.13 */ #include "plugin.h" #include "mpegplayer.h" #include /* Main allocator */ static off_t mem_ptr; static size_t bufsize; static unsigned char* mallocbuf; /* libmpeg2 allocator */ static off_t mpeg2_mem_ptr SHAREDBSS_ATTR; static size_t mpeg2_bufsize SHAREDBSS_ATTR; static unsigned char *mpeg2_mallocbuf SHAREDBSS_ATTR; static unsigned char *mpeg2_bufallocbuf SHAREDBSS_ATTR; #if defined(DEBUG) || defined(SIMULATOR) const char * mpeg_get_reason_str(int reason) { const char *str; switch (reason) { case MPEG2_ALLOC_MPEG2DEC: str = "MPEG2_ALLOC_MPEG2DEC"; break; case MPEG2_ALLOC_CHUNK: str = "MPEG2_ALLOC_CHUNK"; break; case MPEG2_ALLOC_YUV: str = "MPEG2_ALLOC_YUV"; break; case MPEG2_ALLOC_CONVERT_ID: str = "MPEG2_ALLOC_CONVERT_ID"; break; case MPEG2_ALLOC_CONVERTED: str = "MPEG2_ALLOC_CONVERTED"; break; case MPEG_ALLOC_MPEG2_BUFFER: str = "MPEG_ALLOC_MPEG2_BUFFER"; break; case MPEG_ALLOC_AUDIOBUF: str = "MPEG_ALLOC_AUDIOBUF"; break; case MPEG_ALLOC_PCMOUT: str = "MPEG_ALLOC_PCMOUT"; break; case MPEG_ALLOC_DISKBUF: str = "MPEG_ALLOC_DISKBUF"; break; case MPEG_ALLOC_CODEC_MALLOC: str = "MPEG_ALLOC_CODEC_MALLOC"; break; case MPEG_ALLOC_CODEC_CALLOC: str = "MPEG_ALLOC_CODEC_CALLOC"; break; default: str = "Unknown"; } return str; } #endif static void * mpeg_malloc_internal (unsigned char *mallocbuf, off_t *mem_ptr, size_t bufsize, unsigned size, int reason) { void *x; DEBUGF("mpeg_alloc_internal: bs:%lu s:%u reason:%s (%d)\n", (unsigned long)bufsize, size, mpeg_get_reason_str(reason), reason); if ((size_t) (*mem_ptr + size) > bufsize) { DEBUGF("OUT OF MEMORY\n"); return NULL; } x = &mallocbuf[*mem_ptr]; *mem_ptr += (size + 3) & ~3; /* Keep memory 32-bit aligned */ return x; (void)reason; } void *mpeg_malloc(size_t size, mpeg2_alloc_t reason) { return mpeg_malloc_internal(mallocbuf, &mem_ptr, bufsize, size, reason); } void *mpeg_malloc_all(size_t *size_out, mpeg2_alloc_t reason) { /* Can steal all but MIN_MEMMARGIN */ if (bufsize - mem_ptr < MIN_MEMMARGIN) return NULL; *size_out = bufsize - mem_ptr - MIN_MEMMARGIN; return mpeg_malloc(*size_out, reason); } bool mpeg_alloc_init(unsigned char *buf, size_t mallocsize) { mem_ptr = 0; /* Cache-align buffer or 4-byte align */ mallocbuf = buf; bufsize = mallocsize; ALIGN_BUFFER(mallocbuf, bufsize, CACHEALIGN_UP(4)); /* Separate allocator for video */ mpeg2_mem_ptr = 0; mpeg2_mallocbuf = mallocbuf; mpeg2_bufallocbuf = mallocbuf; mpeg2_bufsize = CACHEALIGN_UP(LIBMPEG2_ALLOC_SIZE); if (mpeg_malloc_internal(mallocbuf, &mem_ptr, bufsize, mpeg2_bufsize, MPEG_ALLOC_MPEG2_BUFFER) == NULL) { return false; } IF_COP(rb->cpucache_invalidate()); return true; } /* allocate non-dedicated buffer space which mpeg2_mem_reset will free */ void * mpeg2_malloc(unsigned size, mpeg2_alloc_t reason) { void *ptr = mpeg_malloc_internal(mpeg2_mallocbuf, &mpeg2_mem_ptr, mpeg2_bufsize, size, reason); /* libmpeg2 expects zero-initialized allocations */ if (ptr) rb->memset(ptr, 0, size); return ptr; } /* allocate dedicated buffer - memory behind buffer pointer becomes dedicated so order is important */ void * mpeg2_bufalloc(unsigned size, mpeg2_alloc_t reason) { void *buf = mpeg2_malloc(size, reason); if (buf == NULL) return NULL; mpeg2_bufallocbuf = &mpeg2_mallocbuf[mpeg2_mem_ptr]; return buf; } /* return unused buffer portion and size */ void * mpeg2_get_buf(size_t *size) { if ((size_t)mpeg2_mem_ptr + 32 >= mpeg2_bufsize) return NULL; *size = mpeg2_bufsize - mpeg2_mem_ptr; return &mpeg2_mallocbuf[mpeg2_mem_ptr]; } /* de-allocate all non-dedicated buffer space */ void mpeg2_mem_reset(void) { DEBUGF("mpeg2_mem_reset\n"); mpeg2_mem_ptr = mpeg2_bufallocbuf - mpeg2_mallocbuf; } /* The following are expected by libmad */ void * codec_malloc(size_t size) { void* ptr; ptr = mpeg_malloc_internal(mallocbuf, &mem_ptr, bufsize, size, MPEG_ALLOC_CODEC_MALLOC); if (ptr) rb->memset(ptr,0,size); return ptr; } void * codec_calloc(size_t nmemb, size_t size) { void* ptr; ptr = mpeg_malloc_internal(mallocbuf, &mem_ptr, bufsize, nmemb*size, MPEG_ALLOC_CODEC_CALLOC); if (ptr) rb->memset(ptr,0,size); return ptr; } void codec_free(void* ptr) { DEBUGF("codec_free - %p\n", ptr); #if 0 mem_ptr = (void *)ptr - (void *)mallocbuf; #endif (void)ptr; } id='n90' href='#n90'>90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 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/***************************************************************************
*             __________               __   ___.
*   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
*   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
*   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
*   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
*                     \/            \/     \/    \/            \/
* $Id$
*
* JPEG image viewer
* (This is a real mess if it has to be coded in one single C file)
*
* File scrolling addition (C) 2005 Alexander Spyridakis
* Copyright (C) 2004 Jörg Hohensohn aka [IDC]Dragon
* Heavily borrowed from the IJG implementation (C) Thomas G. Lane
* Small & fast downscaling IDCT (C) 2002 by Guido Vollbeding  JPEGclub.org
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
****************************************************************************/

#include "plugin.h"

#include "jpeg_decoder.h"

/* for portability of below JPEG code */
#define MEMSET(p,v,c) rb->memset(p,v,c)
#define MEMCPY(d,s,c) rb->memcpy(d,s,c)
#define INLINE static inline
#define ENDIAN_SWAP16(n) n /* only for poor little endian machines */

/**************** begin JPEG code ********************/

INLINE unsigned range_limit(int value)
{
#if CONFIG_CPU == SH7034
    unsigned tmp;
    asm (  /* Note: Uses knowledge that only low byte of result is used */
        "mov     #-128,%[t]  \n"
        "sub     %[t],%[v]   \n"  /* value -= -128; equals value += 128; */
        "extu.b  %[v],%[t]   \n"
        "cmp/eq  %[v],%[t]   \n"  /* low byte == whole number ? */
        "bt      1f          \n"  /* yes: no overflow */
        "cmp/pz  %[v]        \n"  /* overflow: positive? */
        "subc    %[v],%[v]   \n"  /* %[r] now either 0 or 0xffffffff */
    "1:                      \n"
        : /* outputs */
        [v]"+r"(value),
        [t]"=&r"(tmp)
    );
    return value;
#elif defined(CPU_COLDFIRE)
    asm (  /* Note: Uses knowledge that only the low byte of the result is used */
        "add.l   #128,%[v]   \n"  /* value += 128; */
        "cmp.l   #255,%[v]   \n"  /* overflow? */
        "bls.b   1f          \n"  /* no: return value */
        "spl.b   %[v]        \n"  /* yes: set low byte to appropriate boundary */
    "1:                      \n"
        : /* outputs */
        [v]"+d"(value)
    );
    return value;
#elif defined(CPU_ARM)
    asm (  /* Note: Uses knowledge that only the low byte of the result is used */
        "add     %[v], %[v], #128    \n"  /* value += 128 */
        "cmp     %[v], #255          \n"  /* out of range 0..255? */
        "mvnhi   %[v], %[v], asr #31 \n"  /* yes: set all bits to ~(sign_bit) */
        : /* outputs */
        [v]"+r"(value)
    );
    return value;
#else
    value += 128;

    if ((unsigned)value <= 255)
        return value;

    if (value < 0)
        return 0;

    return 255;
#endif
}

/* IDCT implementation */


#define CONST_BITS 13
#define PASS1_BITS 2


/* Some C compilers fail to reduce "FIX(constant)" at compile time, thus
* causing a lot of useless floating-point operations at run time.
* To get around this we use the following pre-calculated constants.
* If you change CONST_BITS you may want to add appropriate values.
* (With a reasonable C compiler, you can just rely on the FIX() macro...)
*/
#define FIX_0_298631336  2446 /* FIX(0.298631336) */
#define FIX_0_390180644  3196 /* FIX(0.390180644) */
#define FIX_0_541196100  4433 /* FIX(0.541196100) */
#define FIX_0_765366865  6270 /* FIX(0.765366865) */
#define FIX_0_899976223  7373 /* FIX(0.899976223) */
#define FIX_1_175875602  9633 /* FIX(1.175875602) */
#define FIX_1_501321110 12299 /* FIX(1.501321110) */
#define FIX_1_847759065 15137 /* FIX(1.847759065) */
#define FIX_1_961570560 16069 /* FIX(1.961570560) */
#define FIX_2_053119869 16819 /* FIX(2.053119869) */
#define FIX_2_562915447 20995 /* FIX(2.562915447) */
#define FIX_3_072711026 25172 /* FIX(3.072711026) */



/* Multiply an long variable by an long constant to yield an long result.
* For 8-bit samples with the recommended scaling, all the variable
* and constant values involved are no more than 16 bits wide, so a
* 16x16->32 bit multiply can be used instead of a full 32x32 multiply.
* For 12-bit samples, a full 32-bit multiplication will be needed.
*/
#define MULTIPLY16(var,const)  (((short) (var)) * ((short) (const)))


/* Dequantize a coefficient by multiplying it by the multiplier-table
* entry; produce an int result.  In this module, both inputs and result
* are 16 bits or less, so either int or short multiply will work.
*/
/* #define DEQUANTIZE(coef,quantval)  (((int) (coef)) * (quantval)) */
#define DEQUANTIZE MULTIPLY16

/* Descale and correctly round an int value that's scaled by N bits.
* We assume RIGHT_SHIFT rounds towards minus infinity, so adding
* the fudge factor is correct for either sign of X.
*/
#define DESCALE(x,n) (((x) + (1l << ((n)-1))) >> (n))



/*
* Perform dequantization and inverse DCT on one block of coefficients,
* producing a reduced-size 1x1 output block.
*/
void idct1x1(unsigned char* p_byte, int* inptr, int* quantptr, int skip_line)
{
    (void)skip_line; /* unused */
    *p_byte = range_limit(inptr[0] * quantptr[0] >> 3);
}



/*
* Perform dequantization and inverse DCT on one block of coefficients,
* producing a reduced-size 2x2 output block.
*/
void idct2x2(unsigned char* p_byte, int* inptr, int* quantptr, int skip_line)
{
    int tmp0, tmp1, tmp2, tmp3, tmp4, tmp5;
    unsigned char* outptr;

    /* Pass 1: process columns from input, store into work array. */

    /* Column 0 */
    tmp4 = DEQUANTIZE(inptr[8*0], quantptr[8*0]);
    tmp5 = DEQUANTIZE(inptr[8*1], quantptr[8*1]);

    tmp0 = tmp4 + tmp5;
    tmp2 = tmp4 - tmp5;

    /* Column 1 */
    tmp4 = DEQUANTIZE(inptr[8*0+1], quantptr[8*0+1]);
    tmp5 = DEQUANTIZE(inptr[8*1+1], quantptr[8*1+1]);

    tmp1 = tmp4 + tmp5;
    tmp3 = tmp4 - tmp5;

    /* Pass 2: process 2 rows, store into output array. */

    /* Row 0 */
    outptr = p_byte;

    outptr[0] = range_limit((int) DESCALE(tmp0 + tmp1, 3));
    outptr[1] = range_limit((int) DESCALE(tmp0 - tmp1, 3));

    /* Row 1 */
    outptr = p_byte + skip_line;

    outptr[0] = range_limit((int) DESCALE(tmp2 + tmp3, 3));
    outptr[1] = range_limit((int) DESCALE(tmp2 - tmp3, 3));
}



/*
* Perform dequantization and inverse DCT on one block of coefficients,
* producing a reduced-size 4x4 output block.
*/
void idct4x4(unsigned char* p_byte, int* inptr, int* quantptr, int skip_line)
{
    int tmp0, tmp2, tmp10, tmp12;
    int z1, z2, z3;
    int * wsptr;
    unsigned char* outptr;
    int ctr;
    int workspace[4*4]; /* buffers data between passes */

    /* Pass 1: process columns from input, store into work array. */

    wsptr = workspace;
    for (ctr = 0; ctr < 4; ctr++, inptr++, quantptr++, wsptr++)
    {
        /* Even part */

        tmp0 = DEQUANTIZE(inptr[8*0], quantptr[8*0]);
        tmp2 = DEQUANTIZE(inptr[8*2], quantptr[8*2]);

        tmp10 = (tmp0 + tmp2) << PASS1_BITS;
        tmp12 = (tmp0 - tmp2) << PASS1_BITS;

        /* Odd part */
        /* Same rotation as in the even part of the 8x8 LL&M IDCT */

        z2 = DEQUANTIZE(inptr[8*1], quantptr[8*1]);
        z3 = DEQUANTIZE(inptr[8*3], quantptr[8*3]);

        z1 = MULTIPLY16(z2 + z3, FIX_0_541196100);
        tmp0 = DESCALE(z1 + MULTIPLY16(z3, - FIX_1_847759065), CONST_BITS-PASS1_BITS);
        tmp2 = DESCALE(z1 + MULTIPLY16(z2, FIX_0_765366865), CONST_BITS-PASS1_BITS);

        /* Final output stage */

        wsptr[4*0] = (int) (tmp10 + tmp2);
        wsptr[4*3] = (int) (tmp10 - tmp2);
        wsptr[4*1] = (int) (tmp12 + tmp0);
        wsptr[4*2] = (int) (tmp12 - tmp0);
    }

    /* Pass 2: process 4 rows from work array, store into output array. */

    wsptr = workspace;
    for (ctr = 0; ctr < 4; ctr++)
    {
        outptr = p_byte + (ctr*skip_line);
        /* Even part */

        tmp0 = (int) wsptr[0];
        tmp2 = (int) wsptr[2];

        tmp10 = (tmp0 + tmp2) << CONST_BITS;
        tmp12 = (tmp0 - tmp2) << CONST_BITS;

        /* Odd part */
        /* Same rotation as in the even part of the 8x8 LL&M IDCT */

        z2 = (int) wsptr[1];
        z3 = (int) wsptr[3];

        z1 = MULTIPLY16(z2 + z3, FIX_0_541196100);
        tmp0 = z1 + MULTIPLY16(z3, - FIX_1_847759065);
        tmp2 = z1 + MULTIPLY16(z2, FIX_0_765366865);

        /* Final output stage */

        outptr[0] = range_limit((int) DESCALE(tmp10 + tmp2,
            CONST_BITS+PASS1_BITS+3));
        outptr[3] = range_limit((int) DESCALE(tmp10 - tmp2,
            CONST_BITS+PASS1_BITS+3));
        outptr[1] = range_limit((int) DESCALE(tmp12 + tmp0,
            CONST_BITS+PASS1_BITS+3));
        outptr[2] = range_limit((int) DESCALE(tmp12 - tmp0,
            CONST_BITS+PASS1_BITS+3));

        wsptr += 4;     /* advance pointer to next row */
    }
}



/*
* Perform dequantization and inverse DCT on one block of coefficients.
*/
void idct8x8(unsigned char* p_byte, int* inptr, int* quantptr, int skip_line)
{
    long tmp0, tmp1, tmp2, tmp3;
    long tmp10, tmp11, tmp12, tmp13;
    long z1, z2, z3, z4, z5;
    int * wsptr;
    unsigned char* outptr;
    int ctr;
    int workspace[64];  /* buffers data between passes */

    /* Pass 1: process columns from input, store into work array. */
    /* Note results are scaled up by sqrt(8) compared to a true IDCT; */
    /* furthermore, we scale the results by 2**PASS1_BITS. */

    wsptr = workspace;
    for (ctr = 8; ctr > 0; ctr--)
    {
    /* Due to quantization, we will usually find that many of the input
    * coefficients are zero, especially the AC terms.  We can exploit this
    * by short-circuiting the IDCT calculation for any column in which all
    * the AC terms are zero.  In that case each output is equal to the
    * DC coefficient (with scale factor as needed).
    * With typical images and quantization tables, half or more of the
    * column DCT calculations can be simplified this way.
    */

        if ((inptr[8*1] | inptr[8*2] | inptr[8*3]
           | inptr[8*4] | inptr[8*5] | inptr[8*6] | inptr[8*7]) == 0)
        {
            /* AC terms all zero */
            int dcval = DEQUANTIZE(inptr[8*0], quantptr[8*0]) << PASS1_BITS;

            wsptr[8*0] = wsptr[8*1] = wsptr[8*2] = wsptr[8*3] = wsptr[8*4]
                       = wsptr[8*5] = wsptr[8*6] = wsptr[8*7] = dcval;
            inptr++;      /* advance pointers to next column */
            quantptr++;
            wsptr++;
            continue;
        }

        /* Even part: reverse the even part of the forward DCT. */
        /* The rotator is sqrt(2)*c(-6). */

        z2 = DEQUANTIZE(inptr[8*2], quantptr[8*2]);
        z3 = DEQUANTIZE(inptr[8*6], quantptr[8*6]);

        z1 = MULTIPLY16(z2 + z3, FIX_0_541196100);
        tmp2 = z1 + MULTIPLY16(z3, - FIX_1_847759065);
        tmp3 = z1 + MULTIPLY16(z2, FIX_0_765366865);

        z2 = DEQUANTIZE(inptr[8*0], quantptr[8*0]);
        z3 = DEQUANTIZE(inptr[8*4], quantptr[8*4]);

        tmp0 = (z2 + z3) << CONST_BITS;
        tmp1 = (z2 - z3) << CONST_BITS;

        tmp10 = tmp0 + tmp3;
        tmp13 = tmp0 - tmp3;
        tmp11 = tmp1 + tmp2;
        tmp12 = tmp1 - tmp2;

        /* Odd part per figure 8; the matrix is unitary and hence its
           transpose is its inverse.  i0..i3 are y7,y5,y3,y1 respectively. */

        tmp0 = DEQUANTIZE(inptr[8*7], quantptr[8*7]);
        tmp1 = DEQUANTIZE(inptr[8*5], quantptr[8*5]);
        tmp2 = DEQUANTIZE(inptr[8*3], quantptr[8*3]);
        tmp3 = DEQUANTIZE(inptr[8*1], quantptr[8*1]);

        z1 = tmp0 + tmp3;
        z2 = tmp1 + tmp2;
        z3 = tmp0 + tmp2;
        z4 = tmp1 + tmp3;
        z5 = MULTIPLY16(z3 + z4, FIX_1_175875602); /* sqrt(2) * c3 */

        tmp0 = MULTIPLY16(tmp0, FIX_0_298631336); /* sqrt(2) * (-c1+c3+c5-c7) */
        tmp1 = MULTIPLY16(tmp1, FIX_2_053119869); /* sqrt(2) * ( c1+c3-c5+c7) */
        tmp2 = MULTIPLY16(tmp2, FIX_3_072711026); /* sqrt(2) * ( c1+c3+c5-c7) */
        tmp3 = MULTIPLY16(tmp3, FIX_1_501321110); /* sqrt(2) * ( c1+c3-c5-c7) */
        z1 = MULTIPLY16(z1, - FIX_0_899976223); /* sqrt(2) * (c7-c3) */
        z2 = MULTIPLY16(z2, - FIX_2_562915447); /* sqrt(2) * (-c1-c3) */
        z3 = MULTIPLY16(z3, - FIX_1_961570560); /* sqrt(2) * (-c3-c5) */
        z4 = MULTIPLY16(z4, - FIX_0_390180644); /* sqrt(2) * (c5-c3) */

        z3 += z5;
        z4 += z5;

        tmp0 += z1 + z3;
        tmp1 += z2 + z4;
        tmp2 += z2 + z3;
        tmp3 += z1 + z4;

        /* Final output stage: inputs are tmp10..tmp13, tmp0..tmp3 */

        wsptr[8*0] = (int) DESCALE(tmp10 + tmp3, CONST_BITS-PASS1_BITS);
        wsptr[8*7] = (int) DESCALE(tmp10 - tmp3, CONST_BITS-PASS1_BITS);
        wsptr[8*1] = (int) DESCALE(tmp11 + tmp2, CONST_BITS-PASS1_BITS);
        wsptr[8*6] = (int) DESCALE(tmp11 - tmp2, CONST_BITS-PASS1_BITS);
        wsptr[8*2] = (int) DESCALE(tmp12 + tmp1, CONST_BITS-PASS1_BITS);
        wsptr[8*5] = (int) DESCALE(tmp12 - tmp1, CONST_BITS-PASS1_BITS);
        wsptr[8*3] = (int) DESCALE(tmp13 + tmp0, CONST_BITS-PASS1_BITS);
        wsptr[8*4] = (int) DESCALE(tmp13 - tmp0, CONST_BITS-PASS1_BITS);

        inptr++; /* advance pointers to next column */
        quantptr++;
        wsptr++;
    }

    /* Pass 2: process rows from work array, store into output array. */
    /* Note that we must descale the results by a factor of 8 == 2**3, */
    /* and also undo the PASS1_BITS scaling. */

    wsptr = workspace;
    for (ctr = 0; ctr < 8; ctr++)
    {
        outptr = p_byte + (ctr*skip_line);
        /* Rows of zeroes can be exploited in the same way as we did with columns.
        * However, the column calculation has created many nonzero AC terms, so
        * the simplification applies less often (typically 5% to 10% of the time).
        * On machines with very fast multiplication, it's possible that the
        * test takes more time than it's worth.  In that case this section
        * may be commented out.
        */

#ifndef NO_ZERO_ROW_TEST
        if ((wsptr[1] | wsptr[2] | wsptr[3]
           | wsptr[4] | wsptr[5] | wsptr[6] | wsptr[7]) == 0)
        {
            /* AC terms all zero */
            unsigned char dcval = range_limit((int) DESCALE((long) wsptr[0],
                PASS1_BITS+3));

            outptr[0] = dcval;
            outptr[1] = dcval;
            outptr[2] = dcval;
            outptr[3] = dcval;
            outptr[4] = dcval;
            outptr[5] = dcval;
            outptr[6] = dcval;
            outptr[7] = dcval;

            wsptr += 8; /* advance pointer to next row */
            continue;
        }
#endif

        /* Even part: reverse the even part of the forward DCT. */
        /* The rotator is sqrt(2)*c(-6). */

        z2 = (long) wsptr[2];
        z3 = (long) wsptr[6];

        z1 = MULTIPLY16(z2 + z3, FIX_0_541196100);
        tmp2 = z1 + MULTIPLY16(z3, - FIX_1_847759065);
        tmp3 = z1 + MULTIPLY16(z2, FIX_0_765366865);

        tmp0 = ((long) wsptr[0] + (long) wsptr[4]) << CONST_BITS;
        tmp1 = ((long) wsptr[0] - (long) wsptr[4]) << CONST_BITS;

        tmp10 = tmp0 + tmp3;
        tmp13 = tmp0 - tmp3;
        tmp11 = tmp1 + tmp2;
        tmp12 = tmp1 - tmp2;

        /* Odd part per figure 8; the matrix is unitary and hence its
        * transpose is its inverse. i0..i3 are y7,y5,y3,y1 respectively. */

        tmp0 = (long) wsptr[7];
        tmp1 = (long) wsptr[5];
        tmp2 = (long) wsptr[3];
        tmp3 = (long) wsptr[1];

        z1 = tmp0 + tmp3;
        z2 = tmp1 + tmp2;
        z3 = tmp0 + tmp2;
        z4 = tmp1 + tmp3;
        z5 = MULTIPLY16(z3 + z4, FIX_1_175875602); /* sqrt(2) * c3 */

        tmp0 = MULTIPLY16(tmp0, FIX_0_298631336); /* sqrt(2) * (-c1+c3+c5-c7) */
        tmp1 = MULTIPLY16(tmp1, FIX_2_053119869); /* sqrt(2) * ( c1+c3-c5+c7) */
        tmp2 = MULTIPLY16(tmp2, FIX_3_072711026); /* sqrt(2) * ( c1+c3+c5-c7) */
        tmp3 = MULTIPLY16(tmp3, FIX_1_501321110); /* sqrt(2) * ( c1+c3-c5-c7) */
        z1 = MULTIPLY16(z1, - FIX_0_899976223); /* sqrt(2) * (c7-c3) */
        z2 = MULTIPLY16(z2, - FIX_2_562915447); /* sqrt(2) * (-c1-c3) */
        z3 = MULTIPLY16(z3, - FIX_1_961570560); /* sqrt(2) * (-c3-c5) */
        z4 = MULTIPLY16(z4, - FIX_0_390180644); /* sqrt(2) * (c5-c3) */

        z3 += z5;
        z4 += z5;

        tmp0 += z1 + z3;
        tmp1 += z2 + z4;
        tmp2 += z2 + z3;
        tmp3 += z1 + z4;

        /* Final output stage: inputs are tmp10..tmp13, tmp0..tmp3 */

        outptr[0] = range_limit((int) DESCALE(tmp10 + tmp3,
            CONST_BITS+PASS1_BITS+3));
        outptr[7] = range_limit((int) DESCALE(tmp10 - tmp3,
            CONST_BITS+PASS1_BITS+3));
        outptr[1] = range_limit((int) DESCALE(tmp11 + tmp2,
            CONST_BITS+PASS1_BITS+3));
        outptr[6] = range_limit((int) DESCALE(tmp11 - tmp2,
            CONST_BITS+PASS1_BITS+3));
        outptr[2] = range_limit((int) DESCALE(tmp12 + tmp1,
            CONST_BITS+PASS1_BITS+3));
        outptr[5] = range_limit((int) DESCALE(tmp12 - tmp1,
            CONST_BITS+PASS1_BITS+3));
        outptr[3] = range_limit((int) DESCALE(tmp13 + tmp0,
            CONST_BITS+PASS1_BITS+3));
        outptr[4] = range_limit((int) DESCALE(tmp13 - tmp0,
            CONST_BITS+PASS1_BITS+3));

        wsptr += 8; /* advance pointer to next row */
    }
}



/* JPEG decoder implementation */

/* Preprocess the JPEG JFIF file */
int process_markers(unsigned char* p_src, long size, struct jpeg* p_jpeg)
{
    unsigned char* p_bytes = p_src;
    int marker_size; /* variable length of marker segment */
    int i, j, n;
    int ret = 0; /* returned flags */

    p_jpeg->p_entropy_end = p_src + size;

    while (p_src < p_bytes + size)
    {
        if (*p_src++ != 0xFF) /* no marker? */
        {
            p_src--; /* it's image data, put it back */
            p_jpeg->p_entropy_data = p_src;
            break; /* exit marker processing */
        }

        switch (*p_src++)
        {
        case 0xFF: /* Fill byte */
            ret |= FILL_FF;
        case 0x00: /* Zero stuffed byte - entropy data */
            p_src--; /* put it back */
            continue;

        case 0xC0: /* SOF Huff  - Baseline DCT */
            {
                ret |= SOF0;
                marker_size = *p_src++ << 8; /* Highbyte */
                marker_size |= *p_src++; /* Lowbyte */
                n = *p_src++; /* sample precision (= 8 or 12) */
                if (n != 8)
                {
                    return(-1); /* Unsupported sample precision */
                }
                p_jpeg->y_size = *p_src++ << 8; /* Highbyte */
                p_jpeg->y_size |= *p_src++; /* Lowbyte */
                p_jpeg->x_size = *p_src++ << 8; /* Highbyte */
                p_jpeg->x_size |= *p_src++; /* Lowbyte */

                n = (marker_size-2-6)/3;
                if (*p_src++ != n || (n != 1 && n != 3))
                {
                    return(-2); /* Unsupported SOF0 component specification */
                }
                for (i=0; i<n; i++)
                {
                    p_jpeg->frameheader[i].ID = *p_src++; /* Component info */
                    p_jpeg->frameheader[i].horizontal_sampling = *p_src >> 4;
                    p_jpeg->frameheader[i].vertical_sampling = *p_src++ & 0x0F;
                    p_jpeg->frameheader[i].quanttable_select = *p_src++;
                    if (p_jpeg->frameheader[i].horizontal_sampling > 2
                     || p_jpeg->frameheader[i].vertical_sampling > 2)
                    return -3; /* Unsupported SOF0 subsampling */
                }
                p_jpeg->blocks = n;
            }
            break;

        case 0xC1: /* SOF Huff  - Extended sequential DCT*/
        case 0xC2: /* SOF Huff  - Progressive DCT*/
        case 0xC3: /* SOF Huff  - Spatial (sequential) lossless*/
        case 0xC5: /* SOF Huff  - Differential sequential DCT*/
        case 0xC6: /* SOF Huff  - Differential progressive DCT*/
        case 0xC7: /* SOF Huff  - Differential spatial*/
        case 0xC8: /* SOF Arith - Reserved for JPEG extensions*/
        case 0xC9: /* SOF Arith - Extended sequential DCT*/
        case 0xCA: /* SOF Arith - Progressive DCT*/
        case 0xCB: /* SOF Arith - Spatial (sequential) lossless*/
        case 0xCD: /* SOF Arith - Differential sequential DCT*/
        case 0xCE: /* SOF Arith - Differential progressive DCT*/
        case 0xCF: /* SOF Arith - Differential spatial*/
            {
                return (-4); /* other DCT model than baseline not implemented */
            }

        case 0xC4: /* Define Huffman Table(s) */
            {
                unsigned char* p_temp;

                ret |= DHT;
                marker_size = *p_src++ << 8; /* Highbyte */
                marker_size |= *p_src++; /* Lowbyte */

                p_temp = p_src;
                while (p_src < p_temp+marker_size-2-17) /* another table */
                {
                    int sum = 0;
                    i = *p_src & 0x0F; /* table index */
                    if (i > 1)
                    {
                        return (-5); /* Huffman table index out of range */
                    }
                    else if (*p_src++ & 0xF0) /* AC table */
                    {
                        for (j=0; j<16; j++)
                        {
                            sum += *p_src;
                            p_jpeg->hufftable[i].huffmancodes_ac[j] = *p_src++;
                        }
                        if(16 + sum > AC_LEN)
                            return -10; /* longer than allowed */

                        for (; j < 16 + sum; j++)
                            p_jpeg->hufftable[i].huffmancodes_ac[j] = *p_src++;
                    }
                    else /* DC table */
                    {
                        for (j=0; j<16; j++)
                        {
                            sum += *p_src;
                            p_jpeg->hufftable[i].huffmancodes_dc[j] = *p_src++;
                        }
                        if(16 + sum > DC_LEN)
                            return -11; /* longer than allowed */

                        for (; j < 16 + sum; j++)
                            p_jpeg->hufftable[i].huffmancodes_dc[j] = *p_src++;
                    }
                } /* while */
                p_src = p_temp+marker_size - 2; /* skip possible residue */
            }
            break;

        case 0xCC: /* Define Arithmetic coding conditioning(s) */
            return(-6); /* Arithmetic coding not supported */

        case 0xD8: /* Start of Image */
        case 0xD9: /* End of Image */
        case 0x01: /* for temp private use arith code */
            break; /* skip parameterless marker */


        case 0xDA: /* Start of Scan */
            {
                ret |= SOS;
                marker_size = *p_src++ << 8; /* Highbyte */
                marker_size |= *p_src++; /* Lowbyte */

                n = (marker_size-2-1-3)/2;
                if (*p_src++ != n || (n != 1 && n != 3))
                {
                    return (-7); /* Unsupported SOS component specification */
                }
                for (i=0; i<n; i++)
                {
                    p_jpeg->scanheader[i].ID = *p_src++;
                    p_jpeg->scanheader[i].DC_select = *p_src >> 4;
                    p_jpeg->scanheader[i].AC_select = *p_src++ & 0x0F;
                }
                p_src += 3; /* skip spectral information */
            }
            break;

        case 0xDB: /* Define quantization Table(s) */
            {
                ret |= DQT;
                marker_size = *p_src++ << 8; /* Highbyte */
                marker_size |= *p_src++; /* Lowbyte */
                n = (marker_size-2)/(QUANT_TABLE_LENGTH+1); /* # of tables */
                for (i=0; i<n; i++)
                {
                    int id = *p_src++; /* ID */
                    if (id >= 4)
                    {
                        return (-8); /* Unsupported quantization table */
                    }
                    /* Read Quantisation table: */
                    for (j=0; j<QUANT_TABLE_LENGTH; j++)
                        p_jpeg->quanttable[id][j] = *p_src++;
                }
            }
            break;

        case 0xDD: /* Define Restart Interval */
            {
                marker_size = *p_src++ << 8; /* Highbyte */
                marker_size |= *p_src++; /* Lowbyte */
                p_jpeg->restart_interval = *p_src++ << 8; /* Highbyte */
                p_jpeg->restart_interval |= *p_src++; /* Lowbyte */
                p_src += marker_size-4; /* skip segment */
            }
            break;

        case 0xDC: /* Define Number of Lines */
        case 0xDE: /* Define Hierarchical progression */
        case 0xDF: /* Expand Reference Component(s) */
        case 0xE0: /* Application Field 0*/
        case 0xE1: /* Application Field 1*/
        case 0xE2: /* Application Field 2*/
        case 0xE3: /* Application Field 3*/
        case 0xE4: /* Application Field 4*/
        case 0xE5: /* Application Field 5*/
        case 0xE6: /* Application Field 6*/
        case 0xE7: /* Application Field 7*/
        case 0xE8: /* Application Field 8*/
        case 0xE9: /* Application Field 9*/
        case 0xEA: /* Application Field 10*/
        case 0xEB: /* Application Field 11*/
        case 0xEC: /* Application Field 12*/
        case 0xED: /* Application Field 13*/
        case 0xEE: /* Application Field 14*/
        case 0xEF: /* Application Field 15*/
        case 0xFE: /* Comment */
            {
                marker_size = *p_src++ << 8; /* Highbyte */
                marker_size |= *p_src++; /* Lowbyte */
                p_src += marker_size-2; /* skip segment */
            }
            break;

        case 0xF0: /* Reserved for JPEG extensions */
        case 0xF1: /* Reserved for JPEG extensions */
        case 0xF2: /* Reserved for JPEG extensions */
        case 0xF3: /* Reserved for JPEG extensions */
        case 0xF4: /* Reserved for JPEG extensions */
        case 0xF5: /* Reserved for JPEG extensions */
        case 0xF6: /* Reserved for JPEG extensions */
        case 0xF7: /* Reserved for JPEG extensions */
        case 0xF8: /* Reserved for JPEG extensions */
        case 0xF9: /* Reserved for JPEG extensions */
        case 0xFA: /* Reserved for JPEG extensions */
        case 0xFB: /* Reserved for JPEG extensions */
        case 0xFC: /* Reserved for JPEG extensions */
        case 0xFD: /* Reserved for JPEG extensions */
        case 0x02: /* Reserved */
        default:
            return (-9); /* Unknown marker */
        } /* switch */
    } /* while */

    return (ret); /* return flags with seen markers */
}


void default_huff_tbl(struct jpeg* p_jpeg)
{
    static const struct huffman_table luma_table =
    {
        {
            0x00,0x01,0x05,0x01,0x01,0x01,0x01,0x01,0x01,0x00,0x00,0x00,0x00,0x00,
            0x00,0x00,0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0A,0x0B
        },
        {
            0x00,0x02,0x01,0x03,0x03,0x02,0x04,0x03,0x05,0x05,0x04,0x04,0x00,0x00,0x01,0x7D,
            0x01,0x02,0x03,0x00,0x04,0x11,0x05,0x12,0x21,0x31,0x41,0x06,0x13,0x51,0x61,0x07,
            0x22,0x71,0x14,0x32,0x81,0x91,0xA1,0x08,0x23,0x42,0xB1,0xC1,0x15,0x52,0xD1,0xF0,
            0x24,0x33,0x62,0x72,0x82,0x09,0x0A,0x16,0x17,0x18,0x19,0x1A,0x25,0x26,0x27,0x28,
            0x29,0x2A,0x34,0x35,0x36,0x37,0x38,0x39,0x3A,0x43,0x44,0x45,0x46,0x47,0x48,0x49,
            0x4A,0x53,0x54,0x55,0x56,0x57,0x58,0x59,0x5A,0x63,0x64,0x65,0x66,0x67,0x68,0x69,
            0x6A,0x73,0x74,0x75,0x76,0x77,0x78,0x79,0x7A,0x83,0x84,0x85,0x86,0x87,0x88,0x89,
            0x8A,0x92,0x93,0x94,0x95,0x96,0x97,0x98,0x99,0x9A,0xA2,0xA3,0xA4,0xA5,0xA6,0xA7,
            0xA8,0xA9,0xAA,0xB2,0xB3,0xB4,0xB5,0xB6,0xB7,0xB8,0xB9,0xBA,0xC2,0xC3,0xC4,0xC5,
            0xC6,0xC7,0xC8,0xC9,0xCA,0xD2,0xD3,0xD4,0xD5,0xD6,0xD7,0xD8,0xD9,0xDA,0xE1,0xE2,
            0xE3,0xE4,0xE5,0xE6,0xE7,0xE8,0xE9,0xEA,0xF1,0xF2,0xF3,0xF4,0xF5,0xF6,0xF7,0xF8,
            0xF9,0xFA
        }
    };

    static const struct huffman_table chroma_table =
    {
        {
            0x00,0x03,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x00,0x00,0x00,
            0x00,0x00,0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0A,0x0B
        },
        {
            0x00,0x02,0x01,0x02,0x04,0x04,0x03,0x04,0x07,0x05,0x04,0x04,0x00,0x01,0x02,0x77,
            0x00,0x01,0x02,0x03,0x11,0x04,0x05,0x21,0x31,0x06,0x12,0x41,0x51,0x07,0x61,0x71,
            0x13,0x22,0x32,0x81,0x08,0x14,0x42,0x91,0xA1,0xB1,0xC1,0x09,0x23,0x33,0x52,0xF0,
            0x15,0x62,0x72,0xD1,0x0A,0x16,0x24,0x34,0xE1,0x25,0xF1,0x17,0x18,0x19,0x1A,0x26,
            0x27,0x28,0x29,0x2A,0x35,0x36,0x37,0x38,0x39,0x3A,0x43,0x44,0x45,0x46,0x47,0x48,
            0x49,0x4A,0x53,0x54,0x55,0x56,0x57,0x58,0x59,0x5A,0x63,0x64,0x65,0x66,0x67,0x68,
            0x69,0x6A,0x73,0x74,0x75,0x76,0x77,0x78,0x79,0x7A,0x82,0x83,0x84,0x85,0x86,0x87,
            0x88,0x89,0x8A,0x92,0x93,0x94,0x95,0x96,0x97,0x98,0x99,0x9A,0xA2,0xA3,0xA4,0xA5,
            0xA6,0xA7,0xA8,0xA9,0xAA,0xB2,0xB3,0xB4,0xB5,0xB6,0xB7,0xB8,0xB9,0xBA,0xC2,0xC3,
            0xC4,0xC5,0xC6,0xC7,0xC8,0xC9,0xCA,0xD2,0xD3,0xD4,0xD5,0xD6,0xD7,0xD8,0xD9,0xDA,
            0xE2,0xE3,0xE4,0xE5,0xE6,0xE7,0xE8,0xE9,0xEA,0xF2,0xF3,0xF4,0xF5,0xF6,0xF7,0xF8,
            0xF9,0xFA
        }
    };

    MEMCPY(&p_jpeg->hufftable[0], &luma_table, sizeof(luma_table));
    MEMCPY(&p_jpeg->hufftable[1], &chroma_table, sizeof(chroma_table));

    return;
}

/* Compute the derived values for a Huffman table */
void fix_huff_tbl(int* htbl, struct derived_tbl* dtbl)
{
    int p, i, l, si;
    int lookbits, ctr;
    char huffsize[257];
    unsigned int huffcode[257];
    unsigned int code;

    dtbl->pub = htbl; /* fill in back link */

    /* Figure C.1: make table of Huffman code length for each symbol */
    /* Note that this is in code-length order. */

    p = 0;
    for (l = 1; l <= 16; l++)
    {    /* all possible code length */
        for (i = 1; i <= (int) htbl[l-1]; i++)  /* all codes per length */
            huffsize[p++] = (char) l;
    }
    huffsize[p] = 0;

    /* Figure C.2: generate the codes themselves */
    /* Note that this is in code-length order. */

    code = 0;
    si = huffsize[0];
    p = 0;
    while (huffsize[p])
    {
        while (((int) huffsize[p]) == si)
        {
            huffcode[p++] = code;
            code++;
        }
        code <<= 1;
        si++;
    }

    /* Figure F.15: generate decoding tables for bit-sequential decoding */

    p = 0;
    for (l = 1; l <= 16; l++)
    {
        if (htbl[l-1])
        {
            dtbl->valptr[l] = p; /* huffval[] index of 1st symbol of code length l */
            dtbl->mincode[l] = huffcode[p]; /* minimum code of length l */
            p += htbl[l-1];
            dtbl->maxcode[l] = huffcode[p-1]; /* maximum code of length l */
        }
        else
        {
            dtbl->maxcode[l] = -1;  /* -1 if no codes of this length */
        }
    }
    dtbl->maxcode[17] = 0xFFFFFL; /* ensures huff_DECODE terminates */

    /* Compute lookahead tables to speed up decoding.
    * First we set all the table entries to 0, indicating "too long";
    * then we iterate through the Huffman codes that are short enough and
    * fill in all the entries that correspond to bit sequences starting
    * with that code.
    */

    MEMSET(dtbl->look_nbits, 0, sizeof(dtbl->look_nbits));

    p = 0;
    for (l = 1; l <= HUFF_LOOKAHEAD; l++)
    {
        for (i = 1; i <= (int) htbl[l-1]; i++, p++)
        {
            /* l = current code's length, p = its index in huffcode[] & huffval[]. */
            /* Generate left-justified code followed by all possible bit sequences */
            lookbits = huffcode[p] << (HUFF_LOOKAHEAD-l);
            for (ctr = 1 << (HUFF_LOOKAHEAD-l); ctr > 0; ctr--)
            {
                dtbl->look_nbits[lookbits] = l;
                dtbl->look_sym[lookbits] = htbl[16+p];
                lookbits++;
            }
        }
    }
}


/* zag[i] is the natural-order position of the i'th element of zigzag order.
 * If the incoming data is corrupted, decode_mcu could attempt to
 * reference values beyond the end of the array.  To avoid a wild store,
 * we put some extra zeroes after the real entries.
 */
static const int zag[] =
{
     0,  1,  8, 16,  9,  2,  3, 10,
    17, 24, 32, 25, 18, 11,  4,  5,
    12, 19, 26, 33, 40, 48, 41, 34,
    27, 20, 13,  6,  7, 14, 21, 28,
    35, 42, 49, 56, 57, 50, 43, 36,
    29, 22, 15, 23, 30, 37, 44, 51,
    58, 59, 52, 45, 38, 31, 39, 46,
    53, 60, 61, 54, 47, 55, 62, 63,
     0,  0,  0,  0,  0,  0,  0,  0, /* extra entries in case k>63 below */
     0,  0,  0,  0,  0,  0,  0,  0
};

void build_lut(struct jpeg* p_jpeg)
{
    int i;
    fix_huff_tbl(p_jpeg->hufftable[0].huffmancodes_dc,
        &p_jpeg->dc_derived_tbls[0]);
    fix_huff_tbl(p_jpeg->hufftable[0].huffmancodes_ac,
        &p_jpeg->ac_derived_tbls[0]);
    fix_huff_tbl(p_jpeg->hufftable[1].huffmancodes_dc,
        &p_jpeg->dc_derived_tbls[1]);
    fix_huff_tbl(p_jpeg->hufftable[1].huffmancodes_ac,
        &p_jpeg->ac_derived_tbls[1]);

    /* build the dequantization tables for the IDCT (De-ZiZagged) */
    for (i=0; i<64; i++)
    {
        p_jpeg->qt_idct[0][zag[i]] = p_jpeg->quanttable[0][i];
        p_jpeg->qt_idct[1][zag[i]] = p_jpeg->quanttable[1][i];
    }

    for (i=0; i<4; i++)
        p_jpeg->store_pos[i] = i; /* default ordering */

    /* assignments for the decoding of blocks */
    if (p_jpeg->frameheader[0].horizontal_sampling == 2
        && p_jpeg->frameheader[0].vertical_sampling == 1)
    {   /* 4:2:2 */
        p_jpeg->blocks = 4;
        p_jpeg->x_mbl = (p_jpeg->x_size+15) / 16;
        p_jpeg->x_phys = p_jpeg->x_mbl * 16;
        p_jpeg->y_mbl = (p_jpeg->y_size+7) / 8;
        p_jpeg->y_phys = p_jpeg->y_mbl * 8;
        p_jpeg->mcu_membership[0] = 0; /* Y1=Y2=0, U=1, V=2 */
        p_jpeg->mcu_membership[1] = 0;
        p_jpeg->mcu_membership[2] = 1;
        p_jpeg->mcu_membership[3] = 2;
        p_jpeg->tab_membership[0] = 0; /* DC, DC, AC, AC */
        p_jpeg->tab_membership[1] = 0;
        p_jpeg->tab_membership[2] = 1;
        p_jpeg->tab_membership[3] = 1;
        p_jpeg->subsample_x[0] = 1;
        p_jpeg->subsample_x[1] = 2;
        p_jpeg->subsample_x[2] = 2;
        p_jpeg->subsample_y[0] = 1;
        p_jpeg->subsample_y[1] = 1;
        p_jpeg->subsample_y[2] = 1;
    }
    if (p_jpeg->frameheader[0].horizontal_sampling == 1
        && p_jpeg->frameheader[0].vertical_sampling == 2)
    {   /* 4:2:2 vertically subsampled */
        p_jpeg->store_pos[1] = 2; /* block positions are mirrored */
        p_jpeg->store_pos[2] = 1;
        p_jpeg->blocks = 4;
        p_jpeg->x_mbl = (p_jpeg->x_size+7) / 8;
        p_jpeg->x_phys = p_jpeg->x_mbl * 8;
        p_jpeg->y_mbl = (p_jpeg->y_size+15) / 16;
        p_jpeg->y_phys = p_jpeg->y_mbl * 16;
        p_jpeg->mcu_membership[0] = 0; /* Y1=Y2=0, U=1, V=2 */
        p_jpeg->mcu_membership[1] = 0;
        p_jpeg->mcu_membership[2] = 1;
        p_jpeg->mcu_membership[3] = 2;
        p_jpeg->tab_membership[0] = 0; /* DC, DC, AC, AC */
        p_jpeg->tab_membership[1] = 0;
        p_jpeg->tab_membership[2] = 1;
        p_jpeg->tab_membership[3] = 1;
        p_jpeg->subsample_x[0] = 1;
        p_jpeg->subsample_x[1] = 1;
        p_jpeg->subsample_x[2] = 1;
        p_jpeg->subsample_y[0] = 1;
        p_jpeg->subsample_y[1] = 2;
        p_jpeg->subsample_y[2] = 2;
    }
    else if (p_jpeg->frameheader[0].horizontal_sampling == 2
        && p_jpeg->frameheader[0].vertical_sampling == 2)
    {   /* 4:2:0 */
        p_jpeg->blocks = 6;
        p_jpeg->x_mbl = (p_jpeg->x_size+15) / 16;
        p_jpeg->x_phys = p_jpeg->x_mbl * 16;
        p_jpeg->y_mbl = (p_jpeg->y_size+15) / 16;
        p_jpeg->y_phys = p_jpeg->y_mbl * 16;
        p_jpeg->mcu_membership[0] = 0;
        p_jpeg->mcu_membership[1] = 0;
        p_jpeg->mcu_membership[2] = 0;
        p_jpeg->mcu_membership[3] = 0;
        p_jpeg->mcu_membership[4] = 1;
        p_jpeg->mcu_membership[5] = 2;
        p_jpeg->tab_membership[0] = 0;
        p_jpeg->tab_membership[1] = 0;
        p_jpeg->tab_membership[2] = 0;
        p_jpeg->tab_membership[3] = 0;
        p_jpeg->tab_membership[4] = 1;
        p_jpeg->tab_membership[5] = 1;
        p_jpeg->subsample_x[0] = 1;
        p_jpeg->subsample_x[1] = 2;
        p_jpeg->subsample_x[2] = 2;
        p_jpeg->subsample_y[0] = 1;
        p_jpeg->subsample_y[1] = 2;
        p_jpeg->subsample_y[2] = 2;
    }
    else if (p_jpeg->frameheader[0].horizontal_sampling == 1
        && p_jpeg->frameheader[0].vertical_sampling == 1)
    {   /* 4:4:4 */
        /* don't overwrite p_jpeg->blocks */
        p_jpeg->x_mbl = (p_jpeg->x_size+7) / 8;
        p_jpeg->x_phys = p_jpeg->x_mbl * 8;
        p_jpeg->y_mbl = (p_jpeg->y_size+7) / 8;
        p_jpeg->y_phys = p_jpeg->y_mbl * 8;
        p_jpeg->mcu_membership[0] = 0;
        p_jpeg->mcu_membership[1] = 1;
        p_jpeg->mcu_membership[2] = 2;
        p_jpeg->tab_membership[0] = 0;
        p_jpeg->tab_membership[1] = 1;
        p_jpeg->tab_membership[2] = 1;
        p_jpeg->subsample_x[0] = 1;
        p_jpeg->subsample_x[1] = 1;
        p_jpeg->subsample_x[2] = 1;
        p_jpeg->subsample_y[0] = 1;
        p_jpeg->subsample_y[1] = 1;
        p_jpeg->subsample_y[2] = 1;
    }
    else
    {
        /* error */
    }

}


/*
* These functions/macros provide the in-line portion of bit fetching.
* Use check_bit_buffer to ensure there are N bits in get_buffer
* before using get_bits, peek_bits, or drop_bits.
*  check_bit_buffer(state,n,action);
*    Ensure there are N bits in get_buffer; if suspend, take action.
*  val = get_bits(n);
*    Fetch next N bits.
*  val = peek_bits(n);
*    Fetch next N bits without removing them from the buffer.
*  drop_bits(n);
*    Discard next N bits.
* The value N should be a simple variable, not an expression, because it
* is evaluated multiple times.
*/

INLINE void check_bit_buffer(struct bitstream* pb, int nbits)
{
    if (pb->bits_left < nbits)
    {   /* nbits is <= 16, so I can always refill 2 bytes in this case */
        unsigned char byte;

        byte = *pb->next_input_byte++;
        if (byte == 0xFF) /* legal marker can be byte stuffing or RSTm */
        {   /* simplification: just skip the (one-byte) marker code */
            pb->next_input_byte++;
        }
        pb->get_buffer = (pb->get_buffer << 8) | byte;

        byte = *pb->next_input_byte++;
        if (byte == 0xFF) /* legal marker can be byte stuffing or RSTm */
        {   /* simplification: just skip the (one-byte) marker code */
            pb->next_input_byte++;
        }
        pb->get_buffer = (pb->get_buffer << 8) | byte;

        pb->bits_left += 16;
    }
}

INLINE int get_bits(struct bitstream* pb, int nbits)
{
    return ((int) (pb->get_buffer >> (pb->bits_left -= nbits))) & (BIT_N(nbits)-1);
}

INLINE int peek_bits(struct bitstream* pb, int nbits)
{
    return ((int) (pb->get_buffer >> (pb->bits_left - nbits))) & (BIT_N(nbits)-1);
}

INLINE void drop_bits(struct bitstream* pb, int nbits)
{
    pb->bits_left -= nbits;
}

/* re-synchronize to entropy data (skip restart marker) */
void search_restart(struct bitstream* pb)
{
    pb->next_input_byte--; /* we may have overread it, taking 2 bytes */
    /* search for a non-byte-padding marker, has to be RSTm or EOS */
    while (pb->next_input_byte < pb->input_end &&
        (pb->next_input_byte[-2] != 0xFF || pb->next_input_byte[-1] == 0x00))
    {
        pb->next_input_byte++;
    }
    pb->bits_left = 0;
}

/* Figure F.12: extend sign bit. */
#define HUFF_EXTEND(x,s)  ((x) < extend_test[s] ? (x) + extend_offset[s] : (x))

static const int extend_test[16] =   /* entry n is 2**(n-1) */
{
    0, 0x0001, 0x0002, 0x0004, 0x0008, 0x0010, 0x0020, 0x0040, 0x0080,
    0x0100, 0x0200, 0x0400, 0x0800, 0x1000, 0x2000, 0x4000
};

static const int extend_offset[16] = /* entry n is (-1 << n) + 1 */
{
    0, ((-1)<<1) + 1, ((-1)<<2) + 1, ((-1)<<3) + 1, ((-1)<<4) + 1,
    ((-1)<<5) + 1, ((-1)<<6) + 1, ((-1)<<7) + 1, ((-1)<<8) + 1,
    ((-1)<<9) + 1, ((-1)<<10) + 1, ((-1)<<11) + 1, ((-1)<<12) + 1,
    ((-1)<<13) + 1, ((-1)<<14) + 1, ((-1)<<15) + 1
};

/* Decode a single value */
INLINE int huff_decode_dc(struct bitstream* bs, struct derived_tbl* tbl)
{
    int nb, look, s, r;

    check_bit_buffer(bs, HUFF_LOOKAHEAD);
    look = peek_bits(bs, HUFF_LOOKAHEAD);
    if ((nb = tbl->look_nbits[look]) != 0)
    {
        drop_bits(bs, nb);
        s = tbl->look_sym[look];
        check_bit_buffer(bs, s);
        r = get_bits(bs, s);
        s = HUFF_EXTEND(r, s);
    }
    else
    {   /*  slow_DECODE(s, HUFF_LOOKAHEAD+1)) < 0); */
        long code;
        nb=HUFF_LOOKAHEAD+1;
        check_bit_buffer(bs, nb);
        code = get_bits(bs, nb);
        while (code > tbl->maxcode[nb])
        {
            code <<= 1;
            check_bit_buffer(bs, 1);
            code |= get_bits(bs, 1);
            nb++;
        }
        if (nb > 16) /* error in Huffman */
        {
            s=0; /* fake a zero, this is most safe */
        }
        else
        {
            s = tbl->pub[16 + tbl->valptr[nb] + ((int) (code - tbl->mincode[nb])) ];
            check_bit_buffer(bs, s);
            r = get_bits(bs, s);
            s = HUFF_EXTEND(r, s);
        }
    } /* end slow decode */
    return s;
}

INLINE int huff_decode_ac(struct bitstream* bs, struct derived_tbl* tbl)
{
    int nb, look, s;

    check_bit_buffer(bs, HUFF_LOOKAHEAD);
    look = peek_bits(bs, HUFF_LOOKAHEAD);
    if ((nb = tbl->look_nbits[look]) != 0)
    {
        drop_bits(bs, nb);
        s = tbl->look_sym[look];
    }
    else
    {   /*  slow_DECODE(s, HUFF_LOOKAHEAD+1)) < 0); */
        long code;
        nb=HUFF_LOOKAHEAD+1;
        check_bit_buffer(bs, nb);
        code = get_bits(bs, nb);
        while (code > tbl->maxcode[nb])
        {
            code <<= 1;
            check_bit_buffer(bs, 1);
            code |= get_bits(bs, 1);
            nb++;
        }
        if (nb > 16) /* error in Huffman */
        {
            s=0; /* fake a zero, this is most safe */
        }
        else
        {
            s = tbl->pub[16 + tbl->valptr[nb] + ((int) (code - tbl->mincode[nb])) ];
        }
    } /* end slow decode */
    return s;
}


#ifdef HAVE_LCD_COLOR

/* JPEG decoder variant for YUV decoding, into 3 different planes */
/*  Note: it keeps the original color subsampling, even if resized. */
int jpeg_decode(struct jpeg* p_jpeg, unsigned char* p_pixel[3],
                int downscale, void (*pf_progress)(int current, int total))
{
    struct bitstream bs; /* bitstream "object" */
    int block[64]; /* decoded DCT coefficients */

    int width, height;
    int skip_line[3]; /* bytes from one line to the next (skip_line) */
    int skip_strip[3], skip_mcu[3]; /* bytes to next DCT row / column */

    int i, x, y; /* loop counter */

    unsigned char* p_line[3] = {p_pixel[0], p_pixel[1], p_pixel[2]};
    unsigned char* p_byte[3]; /* bitmap pointer */

    void (*pf_idct)(unsigned char*, int*, int*, int); /* selected IDCT */
    int k_need; /* AC coefficients needed up to here */
    int zero_need; /* init the block with this many zeros */

    int last_dc_val[3] = {0, 0, 0}; /* or 128 for chroma? */
    int store_offs[4]; /* memory offsets: order of Y11 Y12 Y21 Y22 U V */
    int restart = p_jpeg->restart_interval; /* MCUs until restart marker */

    /* pick the IDCT we want, determine how to work with coefs */
    if (downscale == 1)
    {
        pf_idct = idct8x8;
        k_need = 64; /* all */
        zero_need = 63; /* all */
    }
    else if (downscale == 2)
    {
        pf_idct = idct4x4;
        k_need = 25; /* this far in zig-zag to cover 4*4 */
        zero_need = 27; /* clear this far in linear order */
    }
    else if (downscale == 4)
    {
        pf_idct = idct2x2;
        k_need = 5; /* this far in zig-zag to cover 2*2 */
        zero_need = 9; /* clear this far in linear order */
    }
    else if (downscale == 8)
    {
        pf_idct = idct1x1;
        k_need = 0; /* no AC, not needed */
        zero_need = 0; /* no AC, not needed */
    }
    else return -1; /* not supported */

    /* init bitstream, fake a restart to make it start */
    bs.next_input_byte = p_jpeg->p_entropy_data;
    bs.bits_left = 0;
    bs.input_end = p_jpeg->p_entropy_end;

    width  = p_jpeg->x_phys / downscale;
    height = p_jpeg->y_phys / downscale;
    for (i=0; i<3; i++) /* calculate some strides */
    {
        skip_line[i] = width / p_jpeg->subsample_x[i];
        skip_strip[i] = skip_line[i]
                        * (height / p_jpeg->y_mbl) / p_jpeg->subsample_y[i];
        skip_mcu[i] = width/p_jpeg->x_mbl / p_jpeg->subsample_x[i];
    }

    /* prepare offsets about where to store the different blocks */
    store_offs[p_jpeg->store_pos[0]] = 0;
    store_offs[p_jpeg->store_pos[1]] = 8 / downscale; /* to the right */
    store_offs[p_jpeg->store_pos[2]] = width * 8 / downscale; /* below */
    store_offs[p_jpeg->store_pos[3]] = store_offs[1] + store_offs[2]; /* r+b */

    for(y=0; y<p_jpeg->y_mbl && bs.next_input_byte <= bs.input_end; y++)
    {
        for (i=0; i<3; i++) /* scan line init */
        {
            p_byte[i] = p_line[i];
            p_line[i] += skip_strip[i];
        }
        for (x=0; x<p_jpeg->x_mbl; x++)
        {
            int blkn;

            /* Outer loop handles each block in the MCU */
            for (blkn = 0; blkn < p_jpeg->blocks; blkn++)
            {   /* Decode a single block's worth of coefficients */
                int k = 1; /* coefficient index */
                int s, r; /* huffman values */
                int ci = p_jpeg->mcu_membership[blkn]; /* component index */
                int ti = p_jpeg->tab_membership[blkn]; /* table index */
                struct derived_tbl* dctbl = &p_jpeg->dc_derived_tbls[ti];
                struct derived_tbl* actbl = &p_jpeg->ac_derived_tbls[ti];

                /* Section F.2.2.1: decode the DC coefficient difference */
                s = huff_decode_dc(&bs, dctbl);

                last_dc_val[ci] += s;
                block[0] = last_dc_val[ci]; /* output it (assumes zag[0] = 0) */

                /* coefficient buffer must be cleared */
                MEMSET(block+1, 0, zero_need*sizeof(block[0]));

                /* Section F.2.2.2: decode the AC coefficients */
                for (; k < k_need; k++)
                {
                    s = huff_decode_ac(&bs, actbl);
                    r = s >> 4;
                    s &= 15;

                    if (s)
                    {
                        k += r;
                        check_bit_buffer(&bs, s);
                        r = get_bits(&bs, s);
                        block[zag[k]] = HUFF_EXTEND(r, s);
                    }
                    else
                    {
                        if (r != 15)
                        {
                            k = 64;
                            break;
                        }
                        k += r;
                    }
                }  /* for k */
                /* In this path we just discard the values */
                for (; k < 64; k++)
                {
                    s = huff_decode_ac(&bs, actbl);
                    r = s >> 4;
                    s &= 15;

                    if (s)
                    {
                        k += r;
                        check_bit_buffer(&bs, s);
                        drop_bits(&bs, s);
                    }
                    else
                    {
                        if (r != 15)
                            break;
                        k += r;
                    }
                }  /* for k */

                if (ci == 0)
                {   /* Y component needs to bother about block store */
                    pf_idct(p_byte[0]+store_offs[blkn], block,
                        p_jpeg->qt_idct[ti], skip_line[0]);
                }
                else
                {   /* chroma */
                    pf_idct(p_byte[ci], block, p_jpeg->qt_idct[ti],
                        skip_line[ci]);
                }
            } /* for blkn */
            p_byte[0] += skip_mcu[0]; /* unrolled for (i=0; i<3; i++) loop */
            p_byte[1] += skip_mcu[1];
            p_byte[2] += skip_mcu[2];
            if (p_jpeg->restart_interval && --restart == 0)
            {   /* if a restart marker is due: */
                restart = p_jpeg->restart_interval; /* count again */
                search_restart(&bs); /* align the bitstream */
                last_dc_val[0] = last_dc_val[1] =
                                 last_dc_val[2] = 0; /* reset decoder */
            }
        } /* for x */
        if (pf_progress != NULL)
            pf_progress(y, p_jpeg->y_mbl-1); /* notify about decoding progress */
    } /* for y */

    return 0; /* success */
}
#else /* !HAVE_LCD_COLOR */

/* a JPEG decoder specialized in decoding only the luminance (b&w) */
int jpeg_decode(struct jpeg* p_jpeg, unsigned char* p_pixel[1], int downscale,
                void (*pf_progress)(int current, int total))
{
    struct bitstream bs; /* bitstream "object" */
    int block[64]; /* decoded DCT coefficients */

    int width, height;
    int skip_line; /* bytes from one line to the next (skip_line) */
    int skip_strip, skip_mcu; /* bytes to next DCT row / column */

    int x, y; /* loop counter */

    unsigned char* p_line = p_pixel[0];
    unsigned char* p_byte; /* bitmap pointer */

    void (*pf_idct)(unsigned char*, int*, int*, int); /* selected IDCT */
    int k_need; /* AC coefficients needed up to here */
    int zero_need; /* init the block with this many zeros */

    int last_dc_val = 0;
    int store_offs[4]; /* memory offsets: order of Y11 Y12 Y21 Y22 U V */
    int restart = p_jpeg->restart_interval; /* MCUs until restart marker */

    /* pick the IDCT we want, determine how to work with coefs */
    if (downscale == 1)
    {
        pf_idct = idct8x8;
        k_need = 64; /* all */
        zero_need = 63; /* all */
    }
    else if (downscale == 2)
    {
        pf_idct = idct4x4;
        k_need = 25; /* this far in zig-zag to cover 4*4 */
        zero_need = 27; /* clear this far in linear order */
    }
    else if (downscale == 4)
    {
        pf_idct = idct2x2;
        k_need = 5; /* this far in zig-zag to cover 2*2 */
        zero_need = 9; /* clear this far in linear order */
    }
    else if (downscale == 8)
    {
        pf_idct = idct1x1;
        k_need = 0; /* no AC, not needed */
        zero_need = 0; /* no AC, not needed */
    }
    else return -1; /* not supported */

    /* init bitstream, fake a restart to make it start */
    bs.next_input_byte = p_jpeg->p_entropy_data;
    bs.bits_left = 0;
    bs.input_end = p_jpeg->p_entropy_end;

    width  = p_jpeg->x_phys / downscale;
    height = p_jpeg->y_phys / downscale;
    skip_line = width;
    skip_strip = skip_line * (height / p_jpeg->y_mbl);
    skip_mcu = (width/p_jpeg->x_mbl);

    /* prepare offsets about where to store the different blocks */
    store_offs[p_jpeg->store_pos[0]] = 0;
    store_offs[p_jpeg->store_pos[1]] = 8 / downscale; /* to the right */
    store_offs[p_jpeg->store_pos[2]] = width * 8 / downscale; /* below */
    store_offs[p_jpeg->store_pos[3]] = store_offs[1] + store_offs[2]; /* r+b */

    for(y=0; y<p_jpeg->y_mbl && bs.next_input_byte <= bs.input_end; y++)
    {
        p_byte = p_line;
        p_line += skip_strip;
        for (x=0; x<p_jpeg->x_mbl; x++)
        {
            int blkn;

            /* Outer loop handles each block in the MCU */
            for (blkn = 0; blkn < p_jpeg->blocks; blkn++)
            {   /* Decode a single block's worth of coefficients */
                int k = 1; /* coefficient index */
                int s, r; /* huffman values */
                int ci = p_jpeg->mcu_membership[blkn]; /* component index */
                int ti = p_jpeg->tab_membership[blkn]; /* table index */
                struct derived_tbl* dctbl = &p_jpeg->dc_derived_tbls[ti];
                struct derived_tbl* actbl = &p_jpeg->ac_derived_tbls[ti];

                /* Section F.2.2.1: decode the DC coefficient difference */
                s = huff_decode_dc(&bs, dctbl);

                if (ci == 0) /* only for Y component */
                {
                    last_dc_val += s;
                    block[0] = last_dc_val; /* output it (assumes zag[0] = 0) */

                    /* coefficient buffer must be cleared */
                    MEMSET(block+1, 0, zero_need*sizeof(block[0]));

                    /* Section F.2.2.2: decode the AC coefficients */
                    for (; k < k_need; k++)
                    {
                        s = huff_decode_ac(&bs, actbl);
                        r = s >> 4;
                        s &= 15;

                        if (s)
                        {
                            k += r;
                            check_bit_buffer(&bs, s);
                            r = get_bits(&bs, s);
                            block[zag[k]] = HUFF_EXTEND(r, s);
                        }
                        else
                        {
                            if (r != 15)
                            {
                                k = 64;
                                break;
                            }
                            k += r;
                        }
                    }  /* for k */
                }
                /* In this path we just discard the values */
                for (; k < 64; k++)
                {
                    s = huff_decode_ac(&bs, actbl);
                    r = s >> 4;
                    s &= 15;

                    if (s)
                    {
                        k += r;
                        check_bit_buffer(&bs, s);
                        drop_bits(&bs, s);
                    }
                    else
                    {
                        if (r != 15)
                            break;
                        k += r;
                    }
                }  /* for k */

                if (ci == 0)
                {   /* only for Y component */
                    pf_idct(p_byte+store_offs[blkn], block, p_jpeg->qt_idct[ti],
                        skip_line);
                }
            } /* for blkn */
            p_byte += skip_mcu;
            if (p_jpeg->restart_interval && --restart == 0)
            {   /* if a restart marker is due: */
                restart = p_jpeg->restart_interval; /* count again */
                search_restart(&bs); /* align the bitstream */
                last_dc_val = 0; /* reset decoder */
            }
        } /* for x */
        if (pf_progress != NULL)
            pf_progress(y, p_jpeg->y_mbl-1); /* notify about decoding progress */
    } /* for y */

    return 0; /* success */
}
#endif /* !HAVE_LCD_COLOR */

/**************** end JPEG code ********************/
generated by cgit v1.1 at 2026-05-14 13:57:28 +0000