Files
pico-loader/arm9/source/patches/platform/m3ds/M3DSReadSdSectorsDmaPatchCode.s
2026-05-03 09:18:31 +00:00

149 lines
3.0 KiB
ArmAsm

.cpu arm946e-s
.section "m3ds_readsdsectorsdma", "ax"
.syntax unified
.thumb
// r0 = src sector
// r1 = previous src sector
// r2 = dma channel
// r3 = dst
.global m3ds_readSdSectorsDma
.type m3ds_readSdSectorsDma, %function
m3ds_readSdSectorsDma:
push {r4-r7,lr}
ldr r4, =0x040001A0
movs r7, #0x80
strb r7, [r4,#0x1]
cmp r1, #0 // if first sector
beq sector_loop // first sector, skip poll
subs r1, r0, r1
cmp r1, #1 // if sequential
beq sector_loop_next_sequential
ldr r7, m3ds_readSdSectorsDma_sdStopTransmission_address
blx r7
sector_loop:
// request sd read for sector 0xaabbccdd
// B1 aa bb cc dd 00 00 00
movs r7, #0xB1
strb r7, [r4,#0x8]
lsrs r7, r0, #24
strb r7, [r4,#0x9]
lsrs r7, r0, #16
strb r7, [r4,#0xA]
lsrs r7, r0, #8
strb r7, [r4,#0xB]
lsls r7, r0, #24
lsrs r7, r7, #24 // r7 = dd
str r7, [r4,#0xC] // storing as little-endian puts the bottom 8 bits as first byte
b cmd_poll_loop
sector_loop_next_sequential:
// request sd read for next contiguous sector
// starting from sector 0xaabbccdd
// B2 aa bb cc dd 00 00 00
movs r7, #0xB2
strb r7, [r4,#0x8]
cmd_poll_loop:
ldr r1, =0x04100010
ldr r7, m3ds_readSdSectorsDma_applyCommand_address
blx r7
// Setup data read card command
movs r7, #0xBA
strb r7, [r4,#0x8]
readDataWithDma:
movs r0, r2 // DMA channel
movs r2, r3 // Destination
movs r3, #1
lsls r3, r3, #9 // (1 << 9) = 512 = count
ldr r6, m3ds_readSdSectorsDma_miiCardDmaCopy32Ptr
blx r6
BA_data_dma:
movs r7, #0xC0 // select rom mode, with irq
strb r7, [r4,#0x1]
movs r7, #0xA1
strb r7, [r4,#0x7]
pop {r4-r7,pc}
.balign 4
.global m3ds_readSdSectorsDma_miiCardDmaCopy32Ptr
m3ds_readSdSectorsDma_miiCardDmaCopy32Ptr:
.word 0
.global m3ds_readSdSectorsDma_applyCommand_address
m3ds_readSdSectorsDma_applyCommand_address:
.word 0
.global m3ds_readSdSectorsDma_sdStopTransmission_address
m3ds_readSdSectorsDma_sdStopTransmission_address:
.word 0
.pool
.section "m3ds_readsdsectorsdma_helper", "ax"
.global m3ds_readSdSectorsDma_applyCommand
.type m3ds_readSdSectorsDma_applyCommand, %function
m3ds_readSdSectorsDma_applyCommand:
ldr r7, =0xA7586000
str r7, [r4,#0x4]
cmd_poll_transfer_loop:
ldrb r7, [r4,#0x6]
lsrs r7, r7, #8
bcc cmd_poll_check_transfer_end
ldr r5, [r1]
cmd_poll_check_transfer_end:
ldrb r7, [r4,#0x7]
lsrs r7, r7, #8
bcs cmd_poll_transfer_loop
cmp r5, #0
bne m3ds_readSdSectorsDma_applyCommand
bx lr
.balign 4
.pool
.global m3ds_sdStopTransmission
.type m3ds_sdStopTransmission, %function
m3ds_sdStopTransmission:
push {r4-r5,lr}
ldr r4, =0x040001A0
movs r5, #0xB3
str r5, [r4, #0x8]
movs r5, #0
str r5, [r4, #0xC]
ldr r5, =0xA0486100
str r5, [r4, #0x4]
// loop until card is ready
stopSdTransmission_read_loop:
// Check MCCNT1_ENABLE
ldrb r5, [r4,#7]
lsrs r5, r5, #8
bcs stopSdTransmission_read_loop
pop {r4-r5,pc}
.balign 4
.pool
.end