#29438 - Joe_Sextus - Sat Nov 20, 2004 1:19 am
I was wondering if any one has implemented Burst Boot in GNU's syntax. I am not very familar with the ARM assembler and when I translated the Burst Boot code for A22i to GAS syntax the program never (as for as I can tell) receives any SIO IRQs. I am using DevKitArm_r8.
Here's my Code:
In my code the screen starts out blue, then when irq_handler is called by bios it changes the screen color to green. Now when a SIO IRQ is received the screen should turn red, but this never happens.
If I boot this up in an emulator and check the memory locations on REG_IE the value is 0x81 (VBlank and SIO) and 0x4000120 = BOOT like it does in the original.
Any help would be appreciated.
-Joe
Here's my Code:
| Code: |
|
.ARM .ALIGN .GLOBAL main msg_boot: .ascii "BOOT" msg_okay: .ascii "OKAY" msg_brst: .ascii "BRST" irq_handler: mov r8, #0x03E0 strh r8, [r5] mov r1, #0x4000000 @> Base of address of all I/O Registers ldr r0, [r1, #0x200] @\ Read REG_IE & REG_IF and r0, r0, r0, lsr #16 @] check for handled IRQs add r3, r1, #0x200 @] and place back in REG_IF strh r0, [r3, #2] @/ ldrh r3, [r1, #-8] @\ orr r3, r3, r0 @] Mirror REG_IF at REG_IRQ_MIRROR (0x3007FF8) strh r3, [r1, #-8] @/ and r3, r0, #0x80 @\ cmp r3, #0x80 @] Check for the Burst Boot (SIO) IRQ mov r11, r11 moveq r8, #0x001F streqh r8, [r5] ldreq r2, [r1 , #0x120] @] ldreq r3, msg_brst @] if "BRST" received jump to the cmpeq r2, r3 @] Burst Boot Handler mov r11, r11 beq burst_boot @/ @Insert Additional IRQ Handler Code Hear bx lr @> return burst_boot: @requires icoming r1=0x4000000 @Disable DMA Transfers ldr r4, msg_okay @\ Receive transfer length in bytes bl sio_transfer @] and reply "OKAY" mov r2, r0 @/ mov r3, #0x3000000 @\ mov r4, #0 @] Download Burst Loader to burstLoop: @] 0x3000000 and up bl sio_transfer @] stmia r3!, {r0} @] add r4, r4, r0 @] subs r2, r2, #4 @] bhi burstLoop @/ bl sio_transfer @> Send the CRC value back to the master mov r14, #0x3000000 bx lr @b 0x3000000 @> start the loader sio_transfer: str r4, [r1, #0x120] @siodata32 ;-set reply/send data ldr r0, [r1, #0x128] @\ orr r0, r0, #0x80 @] activate slave transfer str r0, [r1,#0x128] @/ sio_wait: @\ ldr r0, [r1, #0x28] @] wait until transfer completed tst r0, #0x80 @] bne sio_wait @/ ldr r0, [r1, #0x120] @> get received data bx lr @> return download_rom_to_ram: bx lr @> return init_interrupts: mov r4, #0x4000000 @> Base of address of all I/O Registers ldr r0, =irq_handler @\ Place the address of irq_handler in str r0, [r4, #-4] @/ REG_IRG_HANDLER (0x3007FFFC) mov r0, #0x0008 @\ Enable the VBlank IRQ in REG_DISPCNT strh r0, [r4, #0x4] @/ mrs r0, cpsr @\ bic r0, r0, #0x80 @] Enable CPU Interrupts (clear i-flag) msr cpsr, r0 @/ mov r0, #0 @\ str r0, [r4, #0x120] @] Init SIO Normal mode, External Clock ldr r0, =0x5080 @] 32-bit, Enable IRQ, transfer Started str r0, [r4, #0x128] @/ ldr r0, msg_boot @\ output "BOOT" to the link str r0, [r4, #0x120] @/ mov r0, #1 @\ Master interrupt enable (REG_IME) str r0, [r4, #0x208] @/ mov r0, #0x81 @\ Enable VBlank and SIO (Burst Boot) str r0, [r4, #0x200] @/ IRQs bx lr @> return main: mov r0, #0xFE @\ Clear all RAM Registers swi 0x10000 @/ except Multiboot Register bl init_interrupts @> install irq_handler mov r4, #0x4000000 @\ Enable video by clearing strh r4, [r4] @] the forced blank bit of @/ REG_DISPCNT mov r5, #0x5000000 mov r8, #0x7C00 mainLoop: swi 0x50000 @> WaitForVIRQ strh r8, [r5] @> b mainLoop .ALIGN .POOL |
In my code the screen starts out blue, then when irq_handler is called by bios it changes the screen color to green. Now when a SIO IRQ is received the screen should turn red, but this never happens.
If I boot this up in an emulator and check the memory locations on REG_IE the value is 0x81 (VBlank and SIO) and 0x4000120 = BOOT like it does in the original.
Any help would be appreciated.
-Joe