mirror of
https://github.com/LNH-team/pico-loader.git
synced 2026-06-02 17:26:48 +02:00
83 lines
1.5 KiB
ArmAsm
83 lines
1.5 KiB
ArmAsm
.cpu arm7tdmi
|
|
.section "r4_readsd", "ax"
|
|
.syntax unified
|
|
.thumb
|
|
|
|
// r0 = src sector
|
|
// r1 = dst
|
|
// r2 = sector count
|
|
.global r4_readSd
|
|
.type r4_readSd, %function
|
|
r4_readSd:
|
|
push {r4-r7,lr}
|
|
ldr r4, =0x040001A0
|
|
movs r3, #0x80
|
|
strb r3, [r4,#1]
|
|
|
|
sector_loop:
|
|
// request sd read at byte address 0xaabbccdd
|
|
// B9 aa bb cc dd 00 00 00
|
|
lsls r7, r0, #9 // sd sector to sd byte address
|
|
movs r3, #0xB9
|
|
strb r3, [r4,#0x8]
|
|
lsrs r3, r7, #24
|
|
strb r3, [r4,#0x9]
|
|
lsrs r3, r7, #16
|
|
strb r3, [r4,#0xA]
|
|
lsrs r3, r7, #8
|
|
strb r3, [r4,#0xB]
|
|
lsls r3, r7, #24
|
|
lsrs r3, r3, #24 // r7 = dd
|
|
str r3, [r4,#0xC] // storing as little-endian puts the bottom 8 bits as first byte
|
|
|
|
ldr r6, =0x04100010
|
|
|
|
B9_poll_loop:
|
|
ldr r3, =0xA7586000
|
|
str r3, [r4,#4]
|
|
|
|
B9_poll_transfer_loop:
|
|
ldrb r3, [r4,#6]
|
|
lsrs r3, r3, #8
|
|
bcc B9_poll_check_transfer_end
|
|
ldr r5, [r6]
|
|
|
|
B9_poll_check_transfer_end:
|
|
ldrb r3, [r4,#7]
|
|
lsrs r3, r3, #8
|
|
bcs B9_poll_transfer_loop
|
|
|
|
cmp r5, #0
|
|
bne B9_poll_loop
|
|
|
|
movs r3, #0xBA
|
|
str r3, [r4,#0x8]
|
|
str r5, [r4,#0xC] // r5 is 0 here
|
|
|
|
ldr r3, =0xA1586000
|
|
str r3, [r4,#4]
|
|
|
|
BA_data_loop:
|
|
ldrb r3, [r4,#6]
|
|
lsrs r3, r3, #8 // check if data is ready
|
|
bcc BA_data_loop_check_transfer_end // if not skip reading
|
|
|
|
ldr r3, [r6]
|
|
stmia r1!, {r3}
|
|
|
|
BA_data_loop_check_transfer_end:
|
|
ldrb r3, [r4,#7]
|
|
lsrs r3, r3, #8 // check if transfer is done
|
|
bcs BA_data_loop
|
|
|
|
adds r0, #1
|
|
subs r2, #1
|
|
bne sector_loop
|
|
|
|
pop {r4-r7,pc}
|
|
|
|
.balign 4
|
|
|
|
.pool
|
|
|
|
.end |