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Diffstat (limited to 'apps/codecs/libgme/nes_cpu_run.h')
-rw-r--r--apps/codecs/libgme/nes_cpu_run.h2244
1 files changed, 1122 insertions, 1122 deletions
diff --git a/apps/codecs/libgme/nes_cpu_run.h b/apps/codecs/libgme/nes_cpu_run.h
index 5b964d5..fd1fea9 100644
--- a/apps/codecs/libgme/nes_cpu_run.h
+++ b/apps/codecs/libgme/nes_cpu_run.h
@@ -1,1122 +1,1122 @@
-// NES 6502 cpu emulator run function
-
-#if 0
-/* Define these macros in the source file before #including this file.
-- Parameters might be expressions, so they are best evaluated only once,
-though they NEVER have side-effects, so multiple evaluation is OK.
-- Output parameters might be a multiple-assignment expression like "a=x",
-so they must NOT be parenthesized.
-- Except where noted, time() and related functions will NOT work
-correctly inside a macro. TIME() is always correct, and FLUSH_TIME() and
-CACHE_TIME() allow the time changing functions to work.
-- Macros "returning" void may use a {} statement block. */
-
- // 0 <= addr <= 0xFFFF + page_size
- // time functions can be used
- int READ_MEM( addr_t );
- void WRITE_MEM( addr_t, int data );
- // 0 <= READ_MEM() <= 0xFF
-
- // 0 <= addr <= 0x1FF
- int READ_LOW( addr_t );
- void WRITE_LOW( addr_t, int data );
- // 0 <= READ_LOW() <= 0xFF
-
- // Often-used instructions attempt these before using a normal memory access.
- // Optional; defaults to READ_MEM() and WRITE_MEM()
- bool CAN_READ_FAST( addr_t ); // if true, uses result of READ_FAST
- void READ_FAST( addr_t, int& out ); // ALWAYS called BEFORE CAN_READ_FAST
- bool CAN_WRITE_FAST( addr_t ); // if true, uses WRITE_FAST instead of WRITE_MEM
- void WRITE_FAST( addr_t, int data );
-
- // Used by instructions most often used to access the NES PPU (LDA abs and BIT abs).
- // Optional; defaults to READ_MEM.
- void READ_PPU( addr_t, int& out );
- // 0 <= out <= 0xFF
-
-// The following can be used within macros:
-
- // Current time
- time_t TIME();
-
- // Allows use of time functions
- void FLUSH_TIME();
-
- // Must be used before end of macro if FLUSH_TIME() was used earlier
- void CACHE_TIME();
-
-// Configuration (optional; commented behavior if defined)
-
- // Emulates dummy reads for indexed instructions
- #define NES_CPU_DUMMY_READS 1
-
- // Optimizes as if map_code( 0, 0x10000 + cpu_padding, FLAT_MEM ) is always in effect
- #define FLAT_MEM my_mem_array
-
- // Expanded just before beginning of code, to help debugger
- #define CPU_BEGIN void my_run_cpu() {
-
-#endif
-
-/* Copyright (C) 2003-2008 Shay Green. This module is free software; you
-can redistribute it and/or modify it under the terms of the GNU Lesser
-General Public License as published by the Free Software Foundation; either
-version 2.1 of the License, or (at your option) any later version. This
-module 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 Lesser General Public License for more
-details. You should have received a copy of the GNU Lesser General Public
-License along with this module; if not, write to the Free Software Foundation,
-Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */
-
-// Allows MWCW debugger to step through code properly
-#ifdef CPU_BEGIN
- CPU_BEGIN
-#endif
-
-// Time
-#define TIME() (s_time + s.base)
-#define FLUSH_TIME() {s.time = s_time - time_offset;}
-#define CACHE_TIME() {s_time = s.time + time_offset;}
-
-// Defaults
-#ifndef CAN_WRITE_FAST
- #define CAN_WRITE_FAST( addr ) 0
- #define WRITE_FAST( addr, data )
-#endif
-
-#ifndef CAN_READ_FAST
- #define CAN_READ_FAST( addr ) 0
- #define READ_FAST( addr, out )
-#endif
-
-#ifndef READ_PPU
- #define READ_PPU( addr, out )\
- {\
- FLUSH_TIME();\
- out = READ_MEM( addr );\
- CACHE_TIME();\
- }
-#endif
-
-#define READ_STACK READ_LOW
-#define WRITE_STACK WRITE_LOW
-
-// Dummy reads
-#ifdef NES_CPU_DUMMY_READS
- // TODO: optimize time handling
- #define DUMMY_READ( addr, idx ) \
- if ( (addr & 0xFF) < idx )\
- {\
- int const time_offset = 1;\
- FLUSH_TIME();\
- READ_MEM( (addr - 0x100) );\
- CACHE_TIME();\
- }
-#else
- #define DUMMY_READ( addr, idx )
-#endif
-
-// Code
-#ifdef FLAT_MEM
- #define CODE_PAGE( addr ) (FLAT_MEM)
- #define CODE_OFFSET( addr ) (addr)
-#else
- #define CODE_PAGE( addr ) (s.code_map [NES_CPU_PAGE( addr )])
- #define CODE_OFFSET( addr ) NES_CPU_OFFSET( addr )
-#endif
-#define READ_CODE( addr ) (CODE_PAGE( addr ) [CODE_OFFSET( addr )])
-
-// Stack
-#define SET_SP( v ) (sp = ((v) + 1) | 0x100)
-#define GET_SP() ((sp - 1) & 0xFF)
-#define SP( o ) ((sp + (o - (o>0)*0x100)) | 0x100)
-
-// Truncation
-#define BYTE( n ) ((uint8_t ) (n)) /* (unsigned) n & 0xFF */
-#define SBYTE( n ) ((int8_t ) (n)) /* (BYTE( n ) ^ 0x80) - 0x80 */
-#define WORD( n ) ((uint16_t) (n)) /* (unsigned) n & 0xFFFF */
-
-// Flags with hex value for clarity when used as mask.
-// Stored in indicated variable during emulation.
-int const n80 = 0x80; // nz
-int const v40 = 0x40; // flags
-int const r20 = 0x20;
-int const b10 = 0x10;
-int const d08 = 0x08; // flags
-int const i04 = 0x04; // flags
-int const z02 = 0x02; // nz
-int const c01 = 0x01; // c
-
-#define IS_NEG (nz & 0x8080)
-
-#define GET_FLAGS( out ) \
-{\
- out = flags & (v40 | d08 | i04);\
- out += ((nz >> 8) | nz) & n80;\
- out += c >> 8 & c01;\
- if ( !BYTE( nz ) )\
- out += z02;\
-}
-
-#define SET_FLAGS( in ) \
-{\
- flags = in & (v40 | d08 | i04);\
- c = nz = in << 8;\
- nz += ~in & z02;\
-}
-
-{
- int const time_offset = 0;
-
- // Local state
- struct cpu_state_t s;
- #ifdef FLAT_MEM
- s.base = cpu->cpu_state_.base;
- #else
- s = cpu->cpu_state_;
- #endif
- cpu->cpu_state = &s;
- int s_time = cpu->cpu_state_.time; // helps even on x86
-
- // Registers
- int pc = cpu->r.pc;
- int a = cpu->r.a;
- int x = cpu->r.x;
- int y = cpu->r.y;
- int sp;
- SET_SP( cpu->r.sp );
-
- // Flags
- int flags;
- int c; // carry set if (c & 0x100) != 0
- int nz; // Z set if (nz & 0xFF) == 0, N set if (nz & 0x8080) != 0
- {
- int temp = cpu->r.flags;
- SET_FLAGS( temp );
- }
-
-loop:
-
- // Check all values
- check( (unsigned) sp - 0x100 < 0x100 );
- check( (unsigned) pc < 0x10000 );
- check( (unsigned) a < 0x100 );
- check( (unsigned) x < 0x100 );
- check( (unsigned) y < 0x100 );
-
- // Read instruction
- byte const* instr = CODE_PAGE( pc );
- int opcode;
-
- if ( CODE_OFFSET(~0) == ~0 )
- {
- opcode = instr [pc];
- pc++;
- instr += pc;
- }
- else
- {
- instr += CODE_OFFSET( pc );
- opcode = *instr++;
- pc++;
- }
-
- // local to function in case it helps optimizer
- static byte const clock_table [256] =
- {// 0 1 2 3 4 5 6 7 8 9 A B C D E F
- 0,6,2,8,3,3,5,5,3,2,2,2,4,4,6,6,// 0
- 2,5,2,8,4,4,6,6,2,4,2,7,4,4,7,7,// 1
- 6,6,0,8,3,3,5,5,4,2,2,2,4,4,6,6,// 2
- 2,5,2,8,4,4,6,6,2,4,2,7,4,4,7,7,// 3
- 6,6,2,8,3,3,5,5,3,2,2,2,3,4,6,6,// 4
- 2,5,2,8,4,4,6,6,2,4,2,7,4,4,7,7,// 5
- 6,6,2,8,3,3,5,5,4,2,2,2,5,4,6,6,// 6
- 2,5,2,8,4,4,6,6,2,4,2,7,4,4,7,7,// 7
- 2,6,2,6,3,3,3,3,2,2,2,2,4,4,4,4,// 8
- 2,6,2,6,4,4,4,4,2,5,2,5,5,5,5,5,// 9
- 2,6,2,6,3,3,3,3,2,2,2,2,4,4,4,4,// A
- 2,5,2,5,4,4,4,4,2,4,2,4,4,4,4,4,// B
- 2,6,2,8,3,3,5,5,2,2,2,2,4,4,6,6,// C
- 2,5,2,8,4,4,6,6,2,4,2,7,4,4,7,7,// D
- 2,6,2,8,3,3,5,5,2,2,2,2,4,4,6,6,// E
- 2,5,2,8,4,4,6,6,2,4,2,7,4,4,7,7 // F
- }; // 0x00 was 7 and 0x22 was 2
-
- // Update time
- if ( s_time >= 0 )
- goto out_of_time;
-
- #ifdef CPU_INSTR_HOOK
- { CPU_INSTR_HOOK( (pc-1), (&instr [-1]), a, x, y, GET_SP(), TIME() ); }
- #endif
-
- s_time += clock_table [opcode];
-
- int data;
- data = *instr;
-
- switch ( opcode )
- {
-
-// Macros
-
-#define GET_MSB() (instr [1])
-#define ADD_PAGE( out ) (pc++, out = data + 0x100 * GET_MSB())
-#define GET_ADDR() GET_LE16( instr )
-
-#define PAGE_PENALTY( lsb ) s_time += (lsb) >> 8;
-
-#define INC_DEC( reg, n ) reg = BYTE( nz = reg + n ); goto loop;
-
-#define IND_Y( cross, out ) {\
- int temp = READ_LOW( data ) + y;\
- out = temp + 0x100 * READ_LOW( BYTE( data + 1 ) );\
- cross( temp );\
- }
-
-#define IND_X( out ) {\
- int temp = data + x;\
- out = 0x100 * READ_LOW( BYTE( temp + 1 ) ) + READ_LOW( BYTE( temp ) );\
- }
-
-#define ARITH_ADDR_MODES( op )\
-case op - 0x04: /* (ind,x) */\
- IND_X( data )\
- goto ptr##op;\
-case op + 0x0C: /* (ind),y */\
- IND_Y( PAGE_PENALTY, data )\
- goto ptr##op;\
-case op + 0x10: /* zp,X */\
- data = BYTE( data + x );\
-case op + 0x00: /* zp */\
- data = READ_LOW( data );\
- goto imm##op;\
-case op + 0x14: /* abs,Y */\
- data += y;\
- goto ind##op;\
-case op + 0x18: /* abs,X */\
- data += x;\
-ind##op:\
- PAGE_PENALTY( data );\
-case op + 0x08: /* abs */\
- ADD_PAGE( data );\
-ptr##op:\
- FLUSH_TIME();\
- data = READ_MEM( data );\
- CACHE_TIME();\
-case op + 0x04: /* imm */\
-imm##op:
-
-// TODO: more efficient way to handle negative branch that wraps PC around
-#define BRANCH( cond )\
-{\
- ++pc;\
- if ( !(cond) ) goto loop;\
- s_time++;\
- int offset = SBYTE( data );\
- s_time += (BYTE(pc) + offset) >> 8 & 1;\
- pc = WORD( pc + offset );\
- goto loop;\
-}
-
-// Often-Used
-
- case 0xB5: // LDA zp,x
- a = nz = READ_LOW( BYTE( data + x ) );
- pc++;
- goto loop;
-
- case 0xA5: // LDA zp
- a = nz = READ_LOW( data );
- pc++;
- goto loop;
-
- case 0xD0: // BNE
- BRANCH( BYTE( nz ) );
-
- case 0x20: { // JSR
- int temp = pc + 1;
- pc = GET_ADDR();
- WRITE_STACK( SP( -1 ), temp >> 8 );
- sp = SP( -2 );
- WRITE_STACK( sp, temp );
- goto loop;
- }
-
- case 0x4C: // JMP abs
- pc = GET_ADDR();
- goto loop;
-
- case 0xE8: // INX
- INC_DEC( x, 1 )
-
- case 0x10: // BPL
- BRANCH( !IS_NEG )
-
- ARITH_ADDR_MODES( 0xC5 ) // CMP
- nz = a - data;
- pc++;
- c = ~nz;
- nz &= 0xFF;
- goto loop;
-
- case 0x30: // BMI
- BRANCH( IS_NEG )
-
- case 0xF0: // BEQ
- BRANCH( !BYTE( nz ) );
-
- case 0x95: // STA zp,x
- data = BYTE( data + x );
- case 0x85: // STA zp
- pc++;
- WRITE_LOW( data, a );
- goto loop;
-
- case 0xC8: // INY
- INC_DEC( y, 1 )
-
- case 0xA8: // TAY
- y = a;
- nz = a;
- goto loop;
-
- case 0x98: // TYA
- a = y;
- nz = y;
- goto loop;
-
- case 0xAD:{// LDA abs
- int addr = GET_ADDR();
- pc += 2;
- READ_PPU( addr, a = nz );
- goto loop;
- }
-
- case 0x60: // RTS
- pc = 1 + READ_STACK( sp );
- pc += 0x100 * READ_STACK( SP( 1 ) );
- sp = SP( 2 );
- goto loop;
-
- {
- int addr;
-
- case 0x8D: // STA abs
- addr = GET_ADDR();
- pc += 2;
- if ( CAN_WRITE_FAST( addr ) )
- {
- WRITE_FAST( addr, a );
- goto loop;
- }
- sta_ptr:
- FLUSH_TIME();
- WRITE_MEM( addr, a );
- CACHE_TIME();
- goto loop;
-
- case 0x99: // STA abs,Y
- addr = y + GET_ADDR();
- pc += 2;
- if ( CAN_WRITE_FAST( addr ) )
- {
- WRITE_FAST( addr, a );
- goto loop;
- }
- goto sta_abs_x;
-
- case 0x9D: // STA abs,X (slightly more common than STA abs)
- addr = x + GET_ADDR();
- pc += 2;
- if ( CAN_WRITE_FAST( addr ) )
- {
- WRITE_FAST( addr, a );
- goto loop;
- }
- DUMMY_READ( addr, x );
- sta_abs_x:
- FLUSH_TIME();
- WRITE_MEM( addr, a );
- CACHE_TIME();
- goto loop;
-
- case 0x91: // STA (ind),Y
- #define NO_PAGE_PENALTY( lsb )
- IND_Y( NO_PAGE_PENALTY, addr )
- pc++;
- DUMMY_READ( addr, y );
- goto sta_ptr;
-
- case 0x81: // STA (ind,X)
- IND_X( addr )
- pc++;
- goto sta_ptr;
-
- }
-
- case 0xA9: // LDA #imm
- pc++;
- a = data;
- nz = data;
- goto loop;
-
- // common read instructions
- {
- int addr;
-
- case 0xA1: // LDA (ind,X)
- IND_X( addr )
- pc++;
- goto a_nz_read_addr;
-
- case 0xB1:// LDA (ind),Y
- addr = READ_LOW( data ) + y;
- PAGE_PENALTY( addr );
- addr += 0x100 * READ_LOW( BYTE( data + 1 ) );
- pc++;
- READ_FAST( addr, a = nz );
- if ( CAN_READ_FAST( addr ) )
- goto loop;
- DUMMY_READ( addr, y );
- goto a_nz_read_addr;
-
- case 0xB9: // LDA abs,Y
- PAGE_PENALTY( data + y );
- addr = GET_ADDR() + y;
- pc += 2;
- READ_FAST( addr, a = nz );
- if ( CAN_READ_FAST( addr ) )
- goto loop;
- goto a_nz_read_addr;
-
- case 0xBD: // LDA abs,X
- PAGE_PENALTY( data + x );
- addr = GET_ADDR() + x;
- pc += 2;
- READ_FAST( addr, a = nz );
- if ( CAN_READ_FAST( addr ) )
- goto loop;
- DUMMY_READ( addr, x );
- a_nz_read_addr:
- FLUSH_TIME();
- a = nz = READ_MEM( addr );
- CACHE_TIME();
- goto loop;
-
- }
-
-// Branch
-
- case 0x50: // BVC
- BRANCH( !(flags & v40) )
-
- case 0x70: // BVS
- BRANCH( flags & v40 )
-
- case 0xB0: // BCS
- BRANCH( c & 0x100 )
-
- case 0x90: // BCC
- BRANCH( !(c & 0x100) )
-
-// Load/store
-
- case 0x94: // STY zp,x
- data = BYTE( data + x );
- case 0x84: // STY zp
- pc++;
- WRITE_LOW( data, y );
- goto loop;
-
- case 0x96: // STX zp,y
- data = BYTE( data + y );
- case 0x86: // STX zp
- pc++;
- WRITE_LOW( data, x );
- goto loop;
-
- case 0xB6: // LDX zp,y
- data = BYTE( data + y );
- case 0xA6: // LDX zp
- data = READ_LOW( data );
- case 0xA2: // LDX #imm
- pc++;
- x = data;
- nz = data;
- goto loop;
-
- case 0xB4: // LDY zp,x
- data = BYTE( data + x );
- case 0xA4: // LDY zp
- data = READ_LOW( data );
- case 0xA0: // LDY #imm
- pc++;
- y = data;
- nz = data;
- goto loop;
-
- case 0xBC: // LDY abs,X
- data += x;
- PAGE_PENALTY( data );
- case 0xAC:{// LDY abs
- int addr = data + 0x100 * GET_MSB();
- pc += 2;
- FLUSH_TIME();
- y = nz = READ_MEM( addr );
- CACHE_TIME();
- goto loop;
- }
-
- case 0xBE: // LDX abs,y
- data += y;
- PAGE_PENALTY( data );
- case 0xAE:{// LDX abs
- int addr = data + 0x100 * GET_MSB();
- pc += 2;
- FLUSH_TIME();
- x = nz = READ_MEM( addr );
- CACHE_TIME();
- goto loop;
- }
-
- {
- int temp;
- case 0x8C: // STY abs
- temp = y;
- goto store_abs;
-
- case 0x8E: // STX abs
- temp = x;
- store_abs:
- {
- int addr = GET_ADDR();
- pc += 2;
- if ( CAN_WRITE_FAST( addr ) )
- {
- WRITE_FAST( addr, temp );
- goto loop;
- }
- FLUSH_TIME();
- WRITE_MEM( addr, temp );
- CACHE_TIME();
- goto loop;
- }
- }
-
-// Compare
-
- case 0xEC: {// CPX abs
- int addr = GET_ADDR();
- pc++;
- FLUSH_TIME();
- data = READ_MEM( addr );
- CACHE_TIME();
- goto cpx_data;
- }
-
- case 0xE4: // CPX zp
- data = READ_LOW( data );
- case 0xE0: // CPX #imm
- cpx_data:
- nz = x - data;
- pc++;
- c = ~nz;
- nz &= 0xFF;
- goto loop;
-
- case 0xCC:{// CPY abs
- int addr = GET_ADDR();
- pc++;
- FLUSH_TIME();
- data = READ_MEM( addr );
- CACHE_TIME();
- goto cpy_data;
- }
-
- case 0xC4: // CPY zp
- data = READ_LOW( data );
- case 0xC0: // CPY #imm
- cpy_data:
- nz = y - data;
- pc++;
- c = ~nz;
- nz &= 0xFF;
- goto loop;
-
-// Logical
-
- ARITH_ADDR_MODES( 0x25 ) // AND
- nz = (a &= data);
- pc++;
- goto loop;
-
- ARITH_ADDR_MODES( 0x45 ) // EOR
- nz = (a ^= data);
- pc++;
- goto loop;
-
- ARITH_ADDR_MODES( 0x05 ) // ORA
- nz = (a |= data);
- pc++;
- goto loop;
-
- case 0x2C:{// BIT abs
- int addr = GET_ADDR();
- pc += 2;
- READ_PPU( addr, nz );
- flags = (flags & ~v40) + (nz & v40);
- if ( a & nz )
- goto loop;
- nz <<= 8; // result must be zero, even if N bit is set
- goto loop;
- }
-
- case 0x24: // BIT zp
- nz = READ_LOW( data );
- pc++;
- flags = (flags & ~v40) + (nz & v40);
- if ( a & nz )
- goto loop; // Z should be clear, and nz must be non-zero if nz & a is
- nz <<= 8; // set Z flag without affecting N flag
- goto loop;
-
-// Add/subtract
-
- ARITH_ADDR_MODES( 0xE5 ) // SBC
- case 0xEB: // unofficial equivalent
- data ^= 0xFF;
- goto adc_imm;
-
- ARITH_ADDR_MODES( 0x65 ) // ADC
- adc_imm: {
- int carry = c >> 8 & 1;
- int ov = (a ^ 0x80) + carry + SBYTE( data );
- flags = (flags & ~v40) + (ov >> 2 & v40);
- c = nz = a + data + carry;
- pc++;
- a = BYTE( nz );
- goto loop;
- }
-
-// Shift/rotate
-
- case 0x4A: // LSR A
- c = 0;
- case 0x6A: // ROR A
- nz = c >> 1 & 0x80;
- c = a << 8;
- nz += a >> 1;
- a = nz;
- goto loop;
-
- case 0x0A: // ASL A
- nz = a << 1;
- c = nz;
- a = BYTE( nz );
- goto loop;
-
- case 0x2A: { // ROL A
- nz = a << 1;
- int temp = c >> 8 & 1;
- c = nz;
- nz += temp;
- a = BYTE( nz );
- goto loop;
- }
-
- case 0x5E: // LSR abs,X
- data += x;
- case 0x4E: // LSR abs
- c = 0;
- case 0x6E: // ROR abs
- ror_abs: {
- ADD_PAGE( data );
- FLUSH_TIME();
- int temp = READ_MEM( data );
- nz = (c >> 1 & 0x80) + (temp >> 1);
- c = temp << 8;
- goto rotate_common;
- }
-
- case 0x3E: // ROL abs,X
- data += x;
- goto rol_abs;
-
- case 0x1E: // ASL abs,X
- data += x;
- case 0x0E: // ASL abs
- c = 0;
- case 0x2E: // ROL abs
- rol_abs:
- ADD_PAGE( data );
- nz = c >> 8 & 1;
- FLUSH_TIME();
- nz += (c = READ_MEM( data ) << 1);
- rotate_common:
- pc++;
- WRITE_MEM( data, BYTE( nz ) );
- CACHE_TIME();
- goto loop;
-
- case 0x7E: // ROR abs,X
- data += x;
- goto ror_abs;
-
- case 0x76: // ROR zp,x
- data = BYTE( data + x );
- goto ror_zp;
-
- case 0x56: // LSR zp,x
- data = BYTE( data + x );
- case 0x46: // LSR zp
- c = 0;
- case 0x66: // ROR zp
- ror_zp: {
- int temp = READ_LOW( data );
- nz = (c >> 1 & 0x80) + (temp >> 1);
- c = temp << 8;
- goto write_nz_zp;
- }
-
- case 0x36: // ROL zp,x
- data = BYTE( data + x );
- goto rol_zp;
-
- case 0x16: // ASL zp,x
- data = BYTE( data + x );
- case 0x06: // ASL zp
- c = 0;
- case 0x26: // ROL zp
- rol_zp:
- nz = c >> 8 & 1;
- nz += (c = READ_LOW( data ) << 1);
- goto write_nz_zp;
-
-// Increment/decrement
-
- case 0xCA: // DEX
- INC_DEC( x, -1 )
-
- case 0x88: // DEY
- INC_DEC( y, -1 )
-
- case 0xF6: // INC zp,x
- data = BYTE( data + x );
- case 0xE6: // INC zp
- nz = 1;
- goto add_nz_zp;
-
- case 0xD6: // DEC zp,x
- data = BYTE( data + x );
- case 0xC6: // DEC zp
- nz = -1;
- add_nz_zp:
- nz += READ_LOW( data );
- write_nz_zp:
- pc++;
- WRITE_LOW( data, nz );
- goto loop;
-
- case 0xFE: // INC abs,x
- data = x + GET_ADDR();
- goto inc_ptr;
-
- case 0xEE: // INC abs
- data = GET_ADDR();
- inc_ptr:
- nz = 1;
- goto inc_common;
-
- case 0xDE: // DEC abs,x
- data = x + GET_ADDR();
- goto dec_ptr;
-
- case 0xCE: // DEC abs
- data = GET_ADDR();
- dec_ptr:
- nz = -1;
- inc_common:
- FLUSH_TIME();
- pc += 2;
- nz += READ_MEM( data );
- WRITE_MEM( data, BYTE( nz ) );
- CACHE_TIME();
- goto loop;
-
-// Transfer
-
- case 0xAA: // TAX
- x = nz = a;
- goto loop;
-
- case 0x8A: // TXA
- a = nz = x;
- goto loop;
-
- case 0x9A: // TXS
- SET_SP( x ); // verified (no flag change)
- goto loop;
-
- case 0xBA: // TSX
- x = nz = GET_SP();
- goto loop;
-
-// Stack
-
- case 0x48: // PHA
- sp = SP( -1 );
- WRITE_STACK( sp, a );
- goto loop;
-
- case 0x68: // PLA
- a = nz = READ_STACK( sp );
- sp = SP( 1 );
- goto loop;
-
- case 0x40:{// RTI
- pc = READ_STACK( SP( 1 ) );
- pc += READ_STACK( SP( 2 ) ) * 0x100;
- int temp = READ_STACK( sp );
- sp = SP( 3 );
- data = flags;
- SET_FLAGS( temp );
- cpu->r.flags = flags; // update externally-visible I flag
- int delta = s.base - cpu->irq_time;
- if ( delta <= 0 ) goto loop; // end_time < irq_time
- if ( flags & i04 ) goto loop;
- s_time += delta;
- s.base = cpu->irq_time;
- goto loop;
- }
-
- case 0x28:{// PLP
- int temp = READ_STACK( sp );
- sp = SP( 1 );
- int changed = flags ^ temp;
- SET_FLAGS( temp );
- if ( !(changed & i04) )
- goto loop; // I flag didn't change
- if ( flags & i04 )
- goto handle_sei;
- goto handle_cli;
- }
-
- case 0x08:{// PHP
- int temp;
- GET_FLAGS( temp );
- sp = SP( -1 );
- WRITE_STACK( sp, temp | (b10 | r20) );
- goto loop;
- }
-
- case 0x6C:{// JMP (ind)
- data = GET_ADDR();
- byte const* page = CODE_PAGE( data );
- pc = page [CODE_OFFSET( data )];
- data = (data & 0xFF00) + ((data + 1) & 0xFF);
- pc += page [CODE_OFFSET( data )] * 0x100;
- goto loop;
- }
-
- case 0x00: // BRK
- goto handle_brk;
-
-// Flags
-
- case 0x38: // SEC
- c = 0x100;
- goto loop;
-
- case 0x18: // CLC
- c = 0;
- goto loop;
-
- case 0xB8: // CLV
- flags &= ~v40;
- goto loop;
-
- case 0xD8: // CLD
- flags &= ~d08;
- goto loop;
-
- case 0xF8: // SED
- flags |= d08;
- goto loop;
-
- case 0x58: // CLI
- if ( !(flags & i04) )
- goto loop;
- flags &= ~i04;
- handle_cli: {
- //dprintf( "CLI at %d\n", TIME );
- cpu->r.flags = flags; // update externally-visible I flag
- int delta = s.base - cpu->irq_time;
- if ( delta <= 0 )
- {
- if ( TIME() < cpu->irq_time )
- goto loop;
- goto delayed_cli;
- }
- s.base = cpu->irq_time;
- s_time += delta;
- if ( s_time < 0 )
- goto loop;
-
- if ( delta >= s_time + 1 )
- {
- // delayed irq until after next instruction
- s.base += s_time + 1;
- s_time = -1;
- goto loop;
- }
-
- // TODO: implement
- delayed_cli:
- dprintf( "Delayed CLI not emulated\n" );
- goto loop;
- }
-
- case 0x78: // SEI
- if ( flags & i04 )
- goto loop;
- flags |= i04;
- handle_sei: {
- cpu->r.flags = flags; // update externally-visible I flag
- int delta = s.base - cpu->end_time;
- s.base = cpu->end_time;
- s_time += delta;
- if ( s_time < 0 )
- goto loop;
-
- dprintf( "Delayed SEI not emulated\n" );
- goto loop;
- }
-
-// Unofficial
-
- // SKW - skip word
- case 0x1C: case 0x3C: case 0x5C: case 0x7C: case 0xDC: case 0xFC:
- PAGE_PENALTY( data + x );
- case 0x0C:
- pc++;
- // SKB - skip byte
- case 0x74: case 0x04: case 0x14: case 0x34: case 0x44: case 0x54: case 0x64:
- case 0x80: case 0x82: case 0x89: case 0xC2: case 0xD4: case 0xE2: case 0xF4:
- pc++;
- goto loop;
-
- // NOP
- case 0xEA: case 0x1A: case 0x3A: case 0x5A: case 0x7A: case 0xDA: case 0xFA:
- goto loop;
-
- case halt_opcode: // HLT - halt processor
- if ( pc-- > 0x10000 )
- {
- // handle wrap-around (assumes caller has put page of HLT at 0x10000)
- pc = WORD( pc );
- goto loop;
- }
- case 0x02: case 0x12: case 0x32: case 0x42: case 0x52:
- case 0x62: case 0x72: case 0x92: case 0xB2: case 0xD2: case 0xF2:
- goto stop;
-
-// Unimplemented
-
- case 0xFF: // force 256-entry jump table for optimization purposes
- c |= 1; // compiler doesn't know that this won't affect anything
- default:
- check( (unsigned) opcode < 0x100 );
-
- #ifdef UNIMPL_INSTR
- UNIMPL_INSTR();
- #endif
-
- // At least skip over proper number of bytes instruction uses
- static unsigned char const illop_lens [8] = {
- 0x40, 0x40, 0x40, 0x80, 0x40, 0x40, 0x80, 0xA0
- };
- int opcode = instr [-1];
- int len = illop_lens [opcode >> 2 & 7] >> (opcode << 1 & 6) & 3;
- if ( opcode == 0x9C )
- len = 2;
- pc += len;
-
- // Account for extra clock
- if ( (opcode >> 4) == 0x0B )
- {
- if ( opcode == 0xB3 )
- data = READ_LOW( data );
- if ( opcode != 0xB7 )
- PAGE_PENALTY( data + y );
- }
- goto loop;
- }
- assert( false ); // catch missing 'goto loop' or accidental 'break'
-
- int result_;
-handle_brk:
- pc++;
- result_ = b10 | 4;
-
-#ifdef CPU_DONE
-interrupt:
-#endif
- {
- s_time += 7;
-
- // Save PC and read vector
- WRITE_STACK( SP( -1 ), pc >> 8 );
- WRITE_STACK( SP( -2 ), pc );
- pc = GET_LE16( &READ_CODE( 0xFFFA ) + (result_ & 4) );
-
- // Save flags
- int temp;
- GET_FLAGS( temp );
- temp |= r20 + (result_ & b10); // B flag set for BRK
- sp = SP( -3 );
- WRITE_STACK( sp, temp );
-
- // Update I flag in externally-visible flags
- cpu->r.flags = (flags |= i04);
-
- // Update time
- int delta = s.base - cpu->end_time;
- if ( delta >= 0 )
- goto loop;
- s_time += delta;
- s.base = cpu->end_time;
- goto loop;
- }
-
-out_of_time:
- pc--;
-
- // Optional action that triggers interrupt or changes irq/end time
- #ifdef CPU_DONE
- {
- CPU_DONE( result_ );
- if ( result_ >= 0 )
- goto interrupt;
- if ( s_time < 0 )
- goto loop;
- }
- #endif
-stop:
-
- // Flush cached state
- cpu->r.pc = pc;
- cpu->r.sp = GET_SP();
- cpu->r.a = a;
- cpu->r.x = x;
- cpu->r.y = y;
-
- int temp;
- GET_FLAGS( temp );
- cpu->r.flags = temp;
-
- cpu->cpu_state_.base = s.base;
- cpu->cpu_state_.time = s_time;
- cpu->cpu_state = &cpu->cpu_state_;
-}
+// NES 6502 cpu emulator run function
+
+#if 0
+/* Define these macros in the source file before #including this file.
+- Parameters might be expressions, so they are best evaluated only once,
+though they NEVER have side-effects, so multiple evaluation is OK.
+- Output parameters might be a multiple-assignment expression like "a=x",
+so they must NOT be parenthesized.
+- Except where noted, time() and related functions will NOT work
+correctly inside a macro. TIME() is always correct, and FLUSH_TIME() and
+CACHE_TIME() allow the time changing functions to work.
+- Macros "returning" void may use a {} statement block. */
+
+ // 0 <= addr <= 0xFFFF + page_size
+ // time functions can be used
+ int READ_MEM( addr_t );
+ void WRITE_MEM( addr_t, int data );
+ // 0 <= READ_MEM() <= 0xFF
+
+ // 0 <= addr <= 0x1FF
+ int READ_LOW( addr_t );
+ void WRITE_LOW( addr_t, int data );
+ // 0 <= READ_LOW() <= 0xFF
+
+ // Often-used instructions attempt these before using a normal memory access.
+ // Optional; defaults to READ_MEM() and WRITE_MEM()
+ bool CAN_READ_FAST( addr_t ); // if true, uses result of READ_FAST
+ void READ_FAST( addr_t, int& out ); // ALWAYS called BEFORE CAN_READ_FAST
+ bool CAN_WRITE_FAST( addr_t ); // if true, uses WRITE_FAST instead of WRITE_MEM
+ void WRITE_FAST( addr_t, int data );
+
+ // Used by instructions most often used to access the NES PPU (LDA abs and BIT abs).
+ // Optional; defaults to READ_MEM.
+ void READ_PPU( addr_t, int& out );
+ // 0 <= out <= 0xFF
+
+// The following can be used within macros:
+
+ // Current time
+ time_t TIME();
+
+ // Allows use of time functions
+ void FLUSH_TIME();
+
+ // Must be used before end of macro if FLUSH_TIME() was used earlier
+ void CACHE_TIME();
+
+// Configuration (optional; commented behavior if defined)
+
+ // Emulates dummy reads for indexed instructions
+ #define NES_CPU_DUMMY_READS 1
+
+ // Optimizes as if map_code( 0, 0x10000 + cpu_padding, FLAT_MEM ) is always in effect
+ #define FLAT_MEM my_mem_array
+
+ // Expanded just before beginning of code, to help debugger
+ #define CPU_BEGIN void my_run_cpu() {
+
+#endif
+
+/* Copyright (C) 2003-2008 Shay Green. This module is free software; you
+can redistribute it and/or modify it under the terms of the GNU Lesser
+General Public License as published by the Free Software Foundation; either
+version 2.1 of the License, or (at your option) any later version. This
+module 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 Lesser General Public License for more
+details. You should have received a copy of the GNU Lesser General Public
+License along with this module; if not, write to the Free Software Foundation,
+Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */
+
+// Allows MWCW debugger to step through code properly
+#ifdef CPU_BEGIN
+ CPU_BEGIN
+#endif
+
+// Time
+#define TIME() (s_time + s.base)
+#define FLUSH_TIME() {s.time = s_time - time_offset;}
+#define CACHE_TIME() {s_time = s.time + time_offset;}
+
+// Defaults
+#ifndef CAN_WRITE_FAST
+ #define CAN_WRITE_FAST( addr ) 0
+ #define WRITE_FAST( addr, data )
+#endif
+
+#ifndef CAN_READ_FAST
+ #define CAN_READ_FAST( addr ) 0
+ #define READ_FAST( addr, out )
+#endif
+
+#ifndef READ_PPU
+ #define READ_PPU( addr, out )\
+ {\
+ FLUSH_TIME();\
+ out = READ_MEM( addr );\
+ CACHE_TIME();\
+ }
+#endif
+
+#define READ_STACK READ_LOW
+#define WRITE_STACK WRITE_LOW
+
+// Dummy reads
+#ifdef NES_CPU_DUMMY_READS
+ // TODO: optimize time handling
+ #define DUMMY_READ( addr, idx ) \
+ if ( (addr & 0xFF) < idx )\
+ {\
+ int const time_offset = 1;\
+ FLUSH_TIME();\
+ READ_MEM( (addr - 0x100) );\
+ CACHE_TIME();\
+ }
+#else
+ #define DUMMY_READ( addr, idx )
+#endif
+
+// Code
+#ifdef FLAT_MEM
+ #define CODE_PAGE( addr ) (FLAT_MEM)
+ #define CODE_OFFSET( addr ) (addr)
+#else
+ #define CODE_PAGE( addr ) (s.code_map [NES_CPU_PAGE( addr )])
+ #define CODE_OFFSET( addr ) NES_CPU_OFFSET( addr )
+#endif
+#define READ_CODE( addr ) (CODE_PAGE( addr ) [CODE_OFFSET( addr )])
+
+// Stack
+#define SET_SP( v ) (sp = ((v) + 1) | 0x100)
+#define GET_SP() ((sp - 1) & 0xFF)
+#define SP( o ) ((sp + (o - (o>0)*0x100)) | 0x100)
+
+// Truncation
+#define BYTE( n ) ((uint8_t ) (n)) /* (unsigned) n & 0xFF */
+#define SBYTE( n ) ((int8_t ) (n)) /* (BYTE( n ) ^ 0x80) - 0x80 */
+#define WORD( n ) ((uint16_t) (n)) /* (unsigned) n & 0xFFFF */
+
+// Flags with hex value for clarity when used as mask.
+// Stored in indicated variable during emulation.
+int const n80 = 0x80; // nz
+int const v40 = 0x40; // flags
+int const r20 = 0x20;
+int const b10 = 0x10;
+int const d08 = 0x08; // flags
+int const i04 = 0x04; // flags
+int const z02 = 0x02; // nz
+int const c01 = 0x01; // c
+
+#define IS_NEG (nz & 0x8080)
+
+#define GET_FLAGS( out ) \
+{\
+ out = flags & (v40 | d08 | i04);\
+ out += ((nz >> 8) | nz) & n80;\
+ out += c >> 8 & c01;\
+ if ( !BYTE( nz ) )\
+ out += z02;\
+}
+
+#define SET_FLAGS( in ) \
+{\
+ flags = in & (v40 | d08 | i04);\
+ c = nz = in << 8;\
+ nz += ~in & z02;\
+}
+
+{
+ int const time_offset = 0;
+
+ // Local state
+ struct cpu_state_t s;
+ #ifdef FLAT_MEM
+ s.base = cpu->cpu_state_.base;
+ #else
+ s = cpu->cpu_state_;
+ #endif
+ cpu->cpu_state = &s;
+ int s_time = cpu->cpu_state_.time; // helps even on x86
+
+ // Registers
+ int pc = cpu->r.pc;
+ int a = cpu->r.a;
+ int x = cpu->r.x;
+ int y = cpu->r.y;
+ int sp;
+ SET_SP( cpu->r.sp );
+
+ // Flags
+ int flags;
+ int c; // carry set if (c & 0x100) != 0
+ int nz; // Z set if (nz & 0xFF) == 0, N set if (nz & 0x8080) != 0
+ {
+ int temp = cpu->r.flags;
+ SET_FLAGS( temp );
+ }
+
+loop:
+
+ // Check all values
+ check( (unsigned) sp - 0x100 < 0x100 );
+ check( (unsigned) pc < 0x10000 );
+ check( (unsigned) a < 0x100 );
+ check( (unsigned) x < 0x100 );
+ check( (unsigned) y < 0x100 );
+
+ // Read instruction
+ byte const* instr = CODE_PAGE( pc );
+ int opcode;
+
+ if ( CODE_OFFSET(~0) == ~0 )
+ {
+ opcode = instr [pc];
+ pc++;
+ instr += pc;
+ }
+ else
+ {
+ instr += CODE_OFFSET( pc );
+ opcode = *instr++;
+ pc++;
+ }
+
+ // local to function in case it helps optimizer
+ static byte const clock_table [256] =
+ {// 0 1 2 3 4 5 6 7 8 9 A B C D E F
+ 0,6,2,8,3,3,5,5,3,2,2,2,4,4,6,6,// 0
+ 2,5,2,8,4,4,6,6,2,4,2,7,4,4,7,7,// 1
+ 6,6,0,8,3,3,5,5,4,2,2,2,4,4,6,6,// 2
+ 2,5,2,8,4,4,6,6,2,4,2,7,4,4,7,7,// 3
+ 6,6,2,8,3,3,5,5,3,2,2,2,3,4,6,6,// 4
+ 2,5,2,8,4,4,6,6,2,4,2,7,4,4,7,7,// 5
+ 6,6,2,8,3,3,5,5,4,2,2,2,5,4,6,6,// 6
+ 2,5,2,8,4,4,6,6,2,4,2,7,4,4,7,7,// 7
+ 2,6,2,6,3,3,3,3,2,2,2,2,4,4,4,4,// 8
+ 2,6,2,6,4,4,4,4,2,5,2,5,5,5,5,5,// 9
+ 2,6,2,6,3,3,3,3,2,2,2,2,4,4,4,4,// A
+ 2,5,2,5,4,4,4,4,2,4,2,4,4,4,4,4,// B
+ 2,6,2,8,3,3,5,5,2,2,2,2,4,4,6,6,// C
+ 2,5,2,8,4,4,6,6,2,4,2,7,4,4,7,7,// D
+ 2,6,2,8,3,3,5,5,2,2,2,2,4,4,6,6,// E
+ 2,5,2,8,4,4,6,6,2,4,2,7,4,4,7,7 // F
+ }; // 0x00 was 7 and 0x22 was 2
+
+ // Update time
+ if ( s_time >= 0 )
+ goto out_of_time;
+
+ #ifdef CPU_INSTR_HOOK
+ { CPU_INSTR_HOOK( (pc-1), (&instr [-1]), a, x, y, GET_SP(), TIME() ); }
+ #endif
+
+ s_time += clock_table [opcode];
+
+ int data;
+ data = *instr;
+
+ switch ( opcode )
+ {
+
+// Macros
+
+#define GET_MSB() (instr [1])
+#define ADD_PAGE( out ) (pc++, out = data + 0x100 * GET_MSB())
+#define GET_ADDR() GET_LE16( instr )
+
+#define PAGE_PENALTY( lsb ) s_time += (lsb) >> 8;
+
+#define INC_DEC( reg, n ) reg = BYTE( nz = reg + n ); goto loop;
+
+#define IND_Y( cross, out ) {\
+ int temp = READ_LOW( data ) + y;\
+ out = temp + 0x100 * READ_LOW( BYTE( data + 1 ) );\
+ cross( temp );\
+ }
+
+#define IND_X( out ) {\
+ int temp = data + x;\
+ out = 0x100 * READ_LOW( BYTE( temp + 1 ) ) + READ_LOW( BYTE( temp ) );\
+ }
+
+#define ARITH_ADDR_MODES( op )\
+case op - 0x04: /* (ind,x) */\
+ IND_X( data )\
+ goto ptr##op;\
+case op + 0x0C: /* (ind),y */\
+ IND_Y( PAGE_PENALTY, data )\
+ goto ptr##op;\
+case op + 0x10: /* zp,X */\
+ data = BYTE( data + x );\
+case op + 0x00: /* zp */\
+ data = READ_LOW( data );\
+ goto imm##op;\
+case op + 0x14: /* abs,Y */\
+ data += y;\
+ goto ind##op;\
+case op + 0x18: /* abs,X */\
+ data += x;\
+ind##op:\
+ PAGE_PENALTY( data );\
+case op + 0x08: /* abs */\
+ ADD_PAGE( data );\
+ptr##op:\
+ FLUSH_TIME();\
+ data = READ_MEM( data );\
+ CACHE_TIME();\
+case op + 0x04: /* imm */\
+imm##op:
+
+// TODO: more efficient way to handle negative branch that wraps PC around
+#define BRANCH( cond )\
+{\
+ ++pc;\
+ if ( !(cond) ) goto loop;\
+ s_time++;\
+ int offset = SBYTE( data );\
+ s_time += (BYTE(pc) + offset) >> 8 & 1;\
+ pc = WORD( pc + offset );\
+ goto loop;\
+}
+
+// Often-Used
+
+ case 0xB5: // LDA zp,x
+ a = nz = READ_LOW( BYTE( data + x ) );
+ pc++;
+ goto loop;
+
+ case 0xA5: // LDA zp
+ a = nz = READ_LOW( data );
+ pc++;
+ goto loop;
+
+ case 0xD0: // BNE
+ BRANCH( BYTE( nz ) );
+
+ case 0x20: { // JSR
+ int temp = pc + 1;
+ pc = GET_ADDR();
+ WRITE_STACK( SP( -1 ), temp >> 8 );
+ sp = SP( -2 );
+ WRITE_STACK( sp, temp );
+ goto loop;
+ }
+
+ case 0x4C: // JMP abs
+ pc = GET_ADDR();
+ goto loop;
+
+ case 0xE8: // INX
+ INC_DEC( x, 1 )
+
+ case 0x10: // BPL
+ BRANCH( !IS_NEG )
+
+ ARITH_ADDR_MODES( 0xC5 ) // CMP
+ nz = a - data;
+ pc++;
+ c = ~nz;
+ nz &= 0xFF;
+ goto loop;
+
+ case 0x30: // BMI
+ BRANCH( IS_NEG )
+
+ case 0xF0: // BEQ
+ BRANCH( !BYTE( nz ) );
+
+ case 0x95: // STA zp,x
+ data = BYTE( data + x );
+ case 0x85: // STA zp
+ pc++;
+ WRITE_LOW( data, a );
+ goto loop;
+
+ case 0xC8: // INY
+ INC_DEC( y, 1 )
+
+ case 0xA8: // TAY
+ y = a;
+ nz = a;
+ goto loop;
+
+ case 0x98: // TYA
+ a = y;
+ nz = y;
+ goto loop;
+
+ case 0xAD:{// LDA abs
+ int addr = GET_ADDR();
+ pc += 2;
+ READ_PPU( addr, a = nz );
+ goto loop;
+ }
+
+ case 0x60: // RTS
+ pc = 1 + READ_STACK( sp );
+ pc += 0x100 * READ_STACK( SP( 1 ) );
+ sp = SP( 2 );
+ goto loop;
+
+ {
+ int addr;
+
+ case 0x8D: // STA abs
+ addr = GET_ADDR();
+ pc += 2;
+ if ( CAN_WRITE_FAST( addr ) )
+ {
+ WRITE_FAST( addr, a );
+ goto loop;
+ }
+ sta_ptr:
+ FLUSH_TIME();
+ WRITE_MEM( addr, a );
+ CACHE_TIME();
+ goto loop;
+
+ case 0x99: // STA abs,Y
+ addr = y + GET_ADDR();
+ pc += 2;
+ if ( CAN_WRITE_FAST( addr ) )
+ {
+ WRITE_FAST( addr, a );
+ goto loop;
+ }
+ goto sta_abs_x;
+
+ case 0x9D: // STA abs,X (slightly more common than STA abs)
+ addr = x + GET_ADDR();
+ pc += 2;
+ if ( CAN_WRITE_FAST( addr ) )
+ {
+ WRITE_FAST( addr, a );
+ goto loop;
+ }
+ DUMMY_READ( addr, x );
+ sta_abs_x:
+ FLUSH_TIME();
+ WRITE_MEM( addr, a );
+ CACHE_TIME();
+ goto loop;
+
+ case 0x91: // STA (ind),Y
+ #define NO_PAGE_PENALTY( lsb )
+ IND_Y( NO_PAGE_PENALTY, addr )
+ pc++;
+ DUMMY_READ( addr, y );
+ goto sta_ptr;
+
+ case 0x81: // STA (ind,X)
+ IND_X( addr )
+ pc++;
+ goto sta_ptr;
+
+ }
+
+ case 0xA9: // LDA #imm
+ pc++;
+ a = data;
+ nz = data;
+ goto loop;
+
+ // common read instructions
+ {
+ int addr;
+
+ case 0xA1: // LDA (ind,X)
+ IND_X( addr )
+ pc++;
+ goto a_nz_read_addr;
+
+ case 0xB1:// LDA (ind),Y
+ addr = READ_LOW( data ) + y;
+ PAGE_PENALTY( addr );
+ addr += 0x100 * READ_LOW( BYTE( data + 1 ) );
+ pc++;
+ READ_FAST( addr, a = nz );
+ if ( CAN_READ_FAST( addr ) )
+ goto loop;
+ DUMMY_READ( addr, y );
+ goto a_nz_read_addr;
+
+ case 0xB9: // LDA abs,Y
+ PAGE_PENALTY( data + y );
+ addr = GET_ADDR() + y;
+ pc += 2;
+ READ_FAST( addr, a = nz );
+ if ( CAN_READ_FAST( addr ) )
+ goto loop;
+ goto a_nz_read_addr;
+
+ case 0xBD: // LDA abs,X
+ PAGE_PENALTY( data + x );
+ addr = GET_ADDR() + x;
+ pc += 2;
+ READ_FAST( addr, a = nz );
+ if ( CAN_READ_FAST( addr ) )
+ goto loop;
+ DUMMY_READ( addr, x );
+ a_nz_read_addr:
+ FLUSH_TIME();
+ a = nz = READ_MEM( addr );
+ CACHE_TIME();
+ goto loop;
+
+ }
+
+// Branch
+
+ case 0x50: // BVC
+ BRANCH( !(flags & v40) )
+
+ case 0x70: // BVS
+ BRANCH( flags & v40 )
+
+ case 0xB0: // BCS
+ BRANCH( c & 0x100 )
+
+ case 0x90: // BCC
+ BRANCH( !(c & 0x100) )
+
+// Load/store
+
+ case 0x94: // STY zp,x
+ data = BYTE( data + x );
+ case 0x84: // STY zp
+ pc++;
+ WRITE_LOW( data, y );
+ goto loop;
+
+ case 0x96: // STX zp,y
+ data = BYTE( data + y );
+ case 0x86: // STX zp
+ pc++;
+ WRITE_LOW( data, x );
+ goto loop;
+
+ case 0xB6: // LDX zp,y
+ data = BYTE( data + y );
+ case 0xA6: // LDX zp
+ data = READ_LOW( data );
+ case 0xA2: // LDX #imm
+ pc++;
+ x = data;
+ nz = data;
+ goto loop;
+
+ case 0xB4: // LDY zp,x
+ data = BYTE( data + x );
+ case 0xA4: // LDY zp
+ data = READ_LOW( data );
+ case 0xA0: // LDY #imm
+ pc++;
+ y = data;
+ nz = data;
+ goto loop;
+
+ case 0xBC: // LDY abs,X
+ data += x;
+ PAGE_PENALTY( data );
+ case 0xAC:{// LDY abs
+ int addr = data + 0x100 * GET_MSB();
+ pc += 2;
+ FLUSH_TIME();
+ y = nz = READ_MEM( addr );
+ CACHE_TIME();
+ goto loop;
+ }
+
+ case 0xBE: // LDX abs,y
+ data += y;
+ PAGE_PENALTY( data );
+ case 0xAE:{// LDX abs
+ int addr = data + 0x100 * GET_MSB();
+ pc += 2;
+ FLUSH_TIME();
+ x = nz = READ_MEM( addr );
+ CACHE_TIME();
+ goto loop;
+ }
+
+ {
+ int temp;
+ case 0x8C: // STY abs
+ temp = y;
+ goto store_abs;
+
+ case 0x8E: // STX abs
+ temp = x;
+ store_abs:
+ {
+ int addr = GET_ADDR();
+ pc += 2;
+ if ( CAN_WRITE_FAST( addr ) )
+ {
+ WRITE_FAST( addr, temp );
+ goto loop;
+ }
+ FLUSH_TIME();
+ WRITE_MEM( addr, temp );
+ CACHE_TIME();
+ goto loop;
+ }
+ }
+
+// Compare
+
+ case 0xEC: {// CPX abs
+ int addr = GET_ADDR();
+ pc++;
+ FLUSH_TIME();
+ data = READ_MEM( addr );
+ CACHE_TIME();
+ goto cpx_data;
+ }
+
+ case 0xE4: // CPX zp
+ data = READ_LOW( data );
+ case 0xE0: // CPX #imm
+ cpx_data:
+ nz = x - data;
+ pc++;
+ c = ~nz;
+ nz &= 0xFF;
+ goto loop;
+
+ case 0xCC:{// CPY abs
+ int addr = GET_ADDR();
+ pc++;
+ FLUSH_TIME();
+ data = READ_MEM( addr );
+ CACHE_TIME();
+ goto cpy_data;
+ }
+
+ case 0xC4: // CPY zp
+ data = READ_LOW( data );
+ case 0xC0: // CPY #imm
+ cpy_data:
+ nz = y - data;
+ pc++;
+ c = ~nz;
+ nz &= 0xFF;
+ goto loop;
+
+// Logical
+
+ ARITH_ADDR_MODES( 0x25 ) // AND
+ nz = (a &= data);
+ pc++;
+ goto loop;
+
+ ARITH_ADDR_MODES( 0x45 ) // EOR
+ nz = (a ^= data);
+ pc++;
+ goto loop;
+
+ ARITH_ADDR_MODES( 0x05 ) // ORA
+ nz = (a |= data);
+ pc++;
+ goto loop;
+
+ case 0x2C:{// BIT abs
+ int addr = GET_ADDR();
+ pc += 2;
+ READ_PPU( addr, nz );
+ flags = (flags & ~v40) + (nz & v40);
+ if ( a & nz )
+ goto loop;
+ nz <<= 8; // result must be zero, even if N bit is set
+ goto loop;
+ }
+
+ case 0x24: // BIT zp
+ nz = READ_LOW( data );
+ pc++;
+ flags = (flags & ~v40) + (nz & v40);
+ if ( a & nz )
+ goto loop; // Z should be clear, and nz must be non-zero if nz & a is
+ nz <<= 8; // set Z flag without affecting N flag
+ goto loop;
+
+// Add/subtract
+
+ ARITH_ADDR_MODES( 0xE5 ) // SBC
+ case 0xEB: // unofficial equivalent
+ data ^= 0xFF;
+ goto adc_imm;
+
+ ARITH_ADDR_MODES( 0x65 ) // ADC
+ adc_imm: {
+ int carry = c >> 8 & 1;
+ int ov = (a ^ 0x80) + carry + SBYTE( data );
+ flags = (flags & ~v40) + (ov >> 2 & v40);
+ c = nz = a + data + carry;
+ pc++;
+ a = BYTE( nz );
+ goto loop;
+ }
+
+// Shift/rotate
+
+ case 0x4A: // LSR A
+ c = 0;
+ case 0x6A: // ROR A
+ nz = c >> 1 & 0x80;
+ c = a << 8;
+ nz += a >> 1;
+ a = nz;
+ goto loop;
+
+ case 0x0A: // ASL A
+ nz = a << 1;
+ c = nz;
+ a = BYTE( nz );
+ goto loop;
+
+ case 0x2A: { // ROL A
+ nz = a << 1;
+ int temp = c >> 8 & 1;
+ c = nz;
+ nz += temp;
+ a = BYTE( nz );
+ goto loop;
+ }
+
+ case 0x5E: // LSR abs,X
+ data += x;
+ case 0x4E: // LSR abs
+ c = 0;
+ case 0x6E: // ROR abs
+ ror_abs: {
+ ADD_PAGE( data );
+ FLUSH_TIME();
+ int temp = READ_MEM( data );
+ nz = (c >> 1 & 0x80) + (temp >> 1);
+ c = temp << 8;
+ goto rotate_common;
+ }
+
+ case 0x3E: // ROL abs,X
+ data += x;
+ goto rol_abs;
+
+ case 0x1E: // ASL abs,X
+ data += x;
+ case 0x0E: // ASL abs
+ c = 0;
+ case 0x2E: // ROL abs
+ rol_abs:
+ ADD_PAGE( data );
+ nz = c >> 8 & 1;
+ FLUSH_TIME();
+ nz += (c = READ_MEM( data ) << 1);
+ rotate_common:
+ pc++;
+ WRITE_MEM( data, BYTE( nz ) );
+ CACHE_TIME();
+ goto loop;
+
+ case 0x7E: // ROR abs,X
+ data += x;
+ goto ror_abs;
+
+ case 0x76: // ROR zp,x
+ data = BYTE( data + x );
+ goto ror_zp;
+
+ case 0x56: // LSR zp,x
+ data = BYTE( data + x );
+ case 0x46: // LSR zp
+ c = 0;
+ case 0x66: // ROR zp
+ ror_zp: {
+ int temp = READ_LOW( data );
+ nz = (c >> 1 & 0x80) + (temp >> 1);
+ c = temp << 8;
+ goto write_nz_zp;
+ }
+
+ case 0x36: // ROL zp,x
+ data = BYTE( data + x );
+ goto rol_zp;
+
+ case 0x16: // ASL zp,x
+ data = BYTE( data + x );
+ case 0x06: // ASL zp
+ c = 0;
+ case 0x26: // ROL zp
+ rol_zp:
+ nz = c >> 8 & 1;
+ nz += (c = READ_LOW( data ) << 1);
+ goto write_nz_zp;
+
+// Increment/decrement
+
+ case 0xCA: // DEX
+ INC_DEC( x, -1 )
+
+ case 0x88: // DEY
+ INC_DEC( y, -1 )
+
+ case 0xF6: // INC zp,x
+ data = BYTE( data + x );
+ case 0xE6: // INC zp
+ nz = 1;
+ goto add_nz_zp;
+
+ case 0xD6: // DEC zp,x
+ data = BYTE( data + x );
+ case 0xC6: // DEC zp
+ nz = -1;
+ add_nz_zp:
+ nz += READ_LOW( data );
+ write_nz_zp:
+ pc++;
+ WRITE_LOW( data, nz );
+ goto loop;
+
+ case 0xFE: // INC abs,x
+ data = x + GET_ADDR();
+ goto inc_ptr;
+
+ case 0xEE: // INC abs
+ data = GET_ADDR();
+ inc_ptr:
+ nz = 1;
+ goto inc_common;
+
+ case 0xDE: // DEC abs,x
+ data = x + GET_ADDR();
+ goto dec_ptr;
+
+ case 0xCE: // DEC abs
+ data = GET_ADDR();
+ dec_ptr:
+ nz = -1;
+ inc_common:
+ FLUSH_TIME();
+ pc += 2;
+ nz += READ_MEM( data );
+ WRITE_MEM( data, BYTE( nz ) );
+ CACHE_TIME();
+ goto loop;
+
+// Transfer
+
+ case 0xAA: // TAX
+ x = nz = a;
+ goto loop;
+
+ case 0x8A: // TXA
+ a = nz = x;
+ goto loop;
+
+ case 0x9A: // TXS
+ SET_SP( x ); // verified (no flag change)
+ goto loop;
+
+ case 0xBA: // TSX
+ x = nz = GET_SP();
+ goto loop;
+
+// Stack
+
+ case 0x48: // PHA
+ sp = SP( -1 );
+ WRITE_STACK( sp, a );
+ goto loop;
+
+ case 0x68: // PLA
+ a = nz = READ_STACK( sp );
+ sp = SP( 1 );
+ goto loop;
+
+ case 0x40:{// RTI
+ pc = READ_STACK( SP( 1 ) );
+ pc += READ_STACK( SP( 2 ) ) * 0x100;
+ int temp = READ_STACK( sp );
+ sp = SP( 3 );
+ data = flags;
+ SET_FLAGS( temp );
+ cpu->r.flags = flags; // update externally-visible I flag
+ int delta = s.base - cpu->irq_time;
+ if ( delta <= 0 ) goto loop; // end_time < irq_time
+ if ( flags & i04 ) goto loop;
+ s_time += delta;
+ s.base = cpu->irq_time;
+ goto loop;
+ }
+
+ case 0x28:{// PLP
+ int temp = READ_STACK( sp );
+ sp = SP( 1 );
+ int changed = flags ^ temp;
+ SET_FLAGS( temp );
+ if ( !(changed & i04) )
+ goto loop; // I flag didn't change
+ if ( flags & i04 )
+ goto handle_sei;
+ goto handle_cli;
+ }
+
+ case 0x08:{// PHP
+ int temp;
+ GET_FLAGS( temp );
+ sp = SP( -1 );
+ WRITE_STACK( sp, temp | (b10 | r20) );
+ goto loop;
+ }
+
+ case 0x6C:{// JMP (ind)
+ data = GET_ADDR();
+ byte const* page = CODE_PAGE( data );
+ pc = page [CODE_OFFSET( data )];
+ data = (data & 0xFF00) + ((data + 1) & 0xFF);
+ pc += page [CODE_OFFSET( data )] * 0x100;
+ goto loop;
+ }
+
+ case 0x00: // BRK
+ goto handle_brk;
+
+// Flags
+
+ case 0x38: // SEC
+ c = 0x100;
+ goto loop;
+
+ case 0x18: // CLC
+ c = 0;
+ goto loop;
+
+ case 0xB8: // CLV
+ flags &= ~v40;
+ goto loop;
+
+ case 0xD8: // CLD
+ flags &= ~d08;
+ goto loop;
+
+ case 0xF8: // SED
+ flags |= d08;
+ goto loop;
+
+ case 0x58: // CLI
+ if ( !(flags & i04) )
+ goto loop;
+ flags &= ~i04;
+ handle_cli: {
+ //dprintf( "CLI at %d\n", TIME );
+ cpu->r.flags = flags; // update externally-visible I flag
+ int delta = s.base - cpu->irq_time;
+ if ( delta <= 0 )
+ {
+ if ( TIME() < cpu->irq_time )
+ goto loop;
+ goto delayed_cli;
+ }
+ s.base = cpu->irq_time;
+ s_time += delta;
+ if ( s_time < 0 )
+ goto loop;
+
+ if ( delta >= s_time + 1 )
+ {
+ // delayed irq until after next instruction
+ s.base += s_time + 1;
+ s_time = -1;
+ goto loop;
+ }
+
+ // TODO: implement
+ delayed_cli:
+ dprintf( "Delayed CLI not emulated\n" );
+ goto loop;
+ }
+
+ case 0x78: // SEI
+ if ( flags & i04 )
+ goto loop;
+ flags |= i04;
+ handle_sei: {
+ cpu->r.flags = flags; // update externally-visible I flag
+ int delta = s.base - cpu->end_time;
+ s.base = cpu->end_time;
+ s_time += delta;
+ if ( s_time < 0 )
+ goto loop;
+
+ dprintf( "Delayed SEI not emulated\n" );
+ goto loop;
+ }
+
+// Unofficial
+
+ // SKW - skip word
+ case 0x1C: case 0x3C: case 0x5C: case 0x7C: case 0xDC: case 0xFC:
+ PAGE_PENALTY( data + x );
+ case 0x0C:
+ pc++;
+ // SKB - skip byte
+ case 0x74: case 0x04: case 0x14: case 0x34: case 0x44: case 0x54: case 0x64:
+ case 0x80: case 0x82: case 0x89: case 0xC2: case 0xD4: case 0xE2: case 0xF4:
+ pc++;
+ goto loop;
+
+ // NOP
+ case 0xEA: case 0x1A: case 0x3A: case 0x5A: case 0x7A: case 0xDA: case 0xFA:
+ goto loop;
+
+ case halt_opcode: // HLT - halt processor
+ if ( pc-- > 0x10000 )
+ {
+ // handle wrap-around (assumes caller has put page of HLT at 0x10000)
+ pc = WORD( pc );
+ goto loop;
+ }
+ case 0x02: case 0x12: case 0x32: case 0x42: case 0x52:
+ case 0x62: case 0x72: case 0x92: case 0xB2: case 0xD2: case 0xF2:
+ goto stop;
+
+// Unimplemented
+
+ case 0xFF: // force 256-entry jump table for optimization purposes
+ c |= 1; // compiler doesn't know that this won't affect anything
+ default:
+ check( (unsigned) opcode < 0x100 );
+
+ #ifdef UNIMPL_INSTR
+ UNIMPL_INSTR();
+ #endif
+
+ // At least skip over proper number of bytes instruction uses
+ static unsigned char const illop_lens [8] = {
+ 0x40, 0x40, 0x40, 0x80, 0x40, 0x40, 0x80, 0xA0
+ };
+ int opcode = instr [-1];
+ int len = illop_lens [opcode >> 2 & 7] >> (opcode << 1 & 6) & 3;
+ if ( opcode == 0x9C )
+ len = 2;
+ pc += len;
+
+ // Account for extra clock
+ if ( (opcode >> 4) == 0x0B )
+ {
+ if ( opcode == 0xB3 )
+ data = READ_LOW( data );
+ if ( opcode != 0xB7 )
+ PAGE_PENALTY( data + y );
+ }
+ goto loop;
+ }
+ assert( false ); // catch missing 'goto loop' or accidental 'break'
+
+ int result_;
+handle_brk:
+ pc++;
+ result_ = b10 | 4;
+
+#ifdef CPU_DONE
+interrupt:
+#endif
+ {
+ s_time += 7;
+
+ // Save PC and read vector
+ WRITE_STACK( SP( -1 ), pc >> 8 );
+ WRITE_STACK( SP( -2 ), pc );
+ pc = GET_LE16( &READ_CODE( 0xFFFA ) + (result_ & 4) );
+
+ // Save flags
+ int temp;
+ GET_FLAGS( temp );
+ temp |= r20 + (result_ & b10); // B flag set for BRK
+ sp = SP( -3 );
+ WRITE_STACK( sp, temp );
+
+ // Update I flag in externally-visible flags
+ cpu->r.flags = (flags |= i04);
+
+ // Update time
+ int delta = s.base - cpu->end_time;
+ if ( delta >= 0 )
+ goto loop;
+ s_time += delta;
+ s.base = cpu->end_time;
+ goto loop;
+ }
+
+out_of_time:
+ pc--;
+
+ // Optional action that triggers interrupt or changes irq/end time
+ #ifdef CPU_DONE
+ {
+ CPU_DONE( result_ );
+ if ( result_ >= 0 )
+ goto interrupt;
+ if ( s_time < 0 )
+ goto loop;
+ }
+ #endif
+stop:
+
+ // Flush cached state
+ cpu->r.pc = pc;
+ cpu->r.sp = GET_SP();
+ cpu->r.a = a;
+ cpu->r.x = x;
+ cpu->r.y = y;
+
+ int temp;
+ GET_FLAGS( temp );
+ cpu->r.flags = temp;
+
+ cpu->cpu_state_.base = s.base;
+ cpu->cpu_state_.time = s_time;
+ cpu->cpu_state = &cpu->cpu_state_;
+}
generated by cgit v1.1 at 2026-05-24 06:47:50 +0000