.section    .text
.align      4

.arm

.global     main
.global     _interrupt_disable
.global     _interrupt_enable

.global     usb_write_addr
.global     usb_sz

#define BUFF_ADDR   0x60800000

/* -----------------------------------------------------
 *  vector table
 * -----------------------------------------------------
 */
    ldr    pc,=main
    ldr    pc,=main
    ldr    pc,=main
    ldr    pc,=main
    ldr    pc,=main
    ldr    pc,=main
    ldr    pc,=irq_handler
    ldr    pc,=main

/* -----------------------------------------------------
 *  main
 * -----------------------------------------------------
 */
main:
    /* turn on usb interrupts */
    mov    r0,#0x18000000
    add    r0,r0,#0x80000
    ldr    r1,[r0,#0x10c]
    orr    r1,r1,#0x10000
    str    r1,[r0,#0x10c]

    /* enable usb-bulk */
    add    r0,r0,#0x20000    /* R0 = 0x180A0000 (UDC_BASE) */

    /* enable EP1 */
    mov    r1,#0x190         /* bits 8,7,4 -> 0x190 */
    str    r1,[r0,#0x58]
    
    /* setup receive buffer (must be aligned on dword boundary) */
    ldr    r1,=usb_write_addr
    ldr    r1,[r1]
    str    r1,[r0, #0x60]    /* UDC_DMA1LM_OADDR = usb_write_addr */
    
    /* write DMA_START in UDC_DMA1CTRLO */
    ldr    r1,[r0,#0x5c]
    orr    r1,r1,#2
    str    r1,[r0,#0x5c]

    /* enable bulk_out1 interrupt */
    ldr    r1,[r0,#0x14]   /* UDC_ENINT */
    orr    r1,r1,#0x100    /* EN_BOUT1_INTR */
    str    r1,[r0,#0x14]

    bl     _interrupt_enable
idle:
    b      idle

/* -----------------------------------------------------
 * _interrupt_enable - enables interrupts
 * -----------------------------------------------------
 */
_interrupt_enable:
    mrs    r0,cpsr
    bic    r0,r0,#0x80
    msr    cpsr_c,r0
    mov    pc,lr

/* -----------------------------------------------------
 * _interrupt_disable - disables interrupts
 * -----------------------------------------------------
 */
_interrupt_disable:
    mrs    r0,cpsr
    orr    r0,r0,#0xc0
    msr    cpsr_c,r0
    mov    pc,lr


.section .data
usb_write_addr:
    .word   (BUFF_ADDR-4)

usb_sz:
    .word   (BUFF_ADDR-4)