.section .text
.align 4

.global irq_handler
#define BUFF_ADDR    0x60800000

irq_handler:
    stmfd    sp!,{r0-r7,ip,lr}

    /* get interrupt number */
    mov    r4,#0x18000000
    add    r4,r4,#0x80000
    ldr    r5,[r4,#0x104]
    and    r5,r5,#0x1f
    cmp    r5,#0x10            /* UDC interrupt */

    bleq   udc_irq

    /* clear pending interrupt */
    mov    r3,#1
    mov    r2,r3,LSL r5
    str    r2,[r4,#0x118]

    ldmfd  sp!,{r0-r7,ip,lr}
    subs   pc,lr,#4

udc_irq:
    stmfd  sp!,{r4-r8,lr}

    /* handle usb interrupt */
    ldr    r4,=0x180A0000
    ldr    r5,[r4,#0x18]       /* UDC_INTFLAG */

    /* ep0 in intr */
    tst    r5,#0x04
    beq    bulk_recv_intr
ep0:
    ldr    r5,[r4,#0x40]
    mov    r5,r5,lsr #10
    mov    r5,r5,lsl #10       /* clear lower 10 bits in TX0STAT */
    str    r5,[r4,#0x40]

    /* set buffer addres in UDC_DMA0LM_OADDR */
    mov    r5,#0x60000000
    str    r5,[r4, #0x3c]

    /* write DMA_START in UDC_DMA0CTLO */
    mov    r5,#1
    str    r5,[r4,#0x38]

    ldmfd  sp!,{r4-r8,pc}

/* bulk out interrupt */
bulk_recv_intr:
    tst    r5,#0x100
    ldmeqfd sp!,{r4-r8,pc}

    /* read UDC_RX1STAT */
    ldr    r5,[r4,#0x54]
    mov    r5,r5,lsl #21
    mov    r5,r5,lsr #21       /* r5 = length */

    ldr    r6,=usb_sz
    ldr    r6,[r6]
    ldr    r7,[r6]             /* r7 = total_code_length expected */

    subs   r7,r7,r5
    bne    usb_bulk_out1_recv

    /* copy from buff to the begining of the ram */
    ldr    r0,=BUFF_ADDR
    ldr    r1,[r0,#-4]        /* size */

    ldr    r1,=0x800000       /* buffer size */

    add    r1,r1,r0           /* end address */
    ldr    r2,=0x60000000     /* destination */
1:
    cmp    r1,r0
    ldrhi  r3,[r0],#4
    strhi  r3,[r2],#4
    bhi    1b

    /* execute user code */
    ldr    r0,=0x60000000
    bx     r0                  /* jump to 0x60000000 */

usb_bulk_out1_recv:
    str    r7,[r6]             /* size = size - received */

    ldr    r6,=usb_write_addr
    ldr    r7,[r6]

    add    r7,r7,r5
    str    r7,[r6]             /* usb_write_addr += length */

    str    r7,[r4,#0x60]       /* DMA1LM_OADDR = usb_write_addr */

    mov    r5,#1
    str    r5,[r4,#0x5c]       /* DMA1_CTL0 = ENP_DMA_START */

    ldmfd  sp!,{r4-r8,pc}