DSTT: Add DMA support and reduce code size (#162) Fixes #111

arm9/source/patches/platform/dstt/DsttReadSdDmaPatchCode.s

@@ -0,0 +1,111 @@
+.cpu arm946e-s
+.section "dstt_readsddma", "ax"
+.syntax unified
+.thumb
+
+// r0 = src sector
+// r1 = previous src sector
+// r2 = dma channel
+// r3 = dst
+.global dstt_readSdDma
+.type dstt_readSdDma, %function
+dstt_readSdDma:
+    push {r2-r7,lr}
+
+    ldr r4, =0x040001A0
+
+    movs r3, #0x80
+    strb r3, [r4,#1]
+
+    adr r2, dstt_romSettings
+    // r2 - dstt_romSettings
+    // r3 - dstt_readSdDma_applySectorCommand_address
+    // r5 - dstt_readSdDma_stopTransmission_address
+    // r6 - dstt_readSdDma_waitDataReady_address
+    // r7 - dstt_readSdDma_miiCardDmaCopy32Ptr
+    ldmia r2, {r2, r3, r5, r6, r7}
+
+    cmp r1, #0
+    beq applySector
+
+    subs r1, r0, r1
+    cmp r1, #1 // if sequential
+    beq sector_loop_sequential
+
+    blx r5 // dstt_readSdDma_stopTransmission_address
+
+applySector:
+    blx r3 // dstt_readSdDma_applySectorCommand_address
+
+    b sector_loop
+
+sector_loop_sequential:
+    // set sd host mode DSTT_MODE_RECEIVE_DATA_BLOCK_STOP_CLOCK
+    // 51 00 00 00 00 00 07 00
+    movs r1, #0x51
+    str r1, [r4, #0x8]
+    movs r1, #7
+    lsls r1, r1, #16
+    str r1, [r4, #0xC]
+
+sector_loop:
+    str r2, [r4,#4]
+
+    movs r1, #0x41
+    lsls r1, r1, #20 // r1 = 0x04100000
+
+cmd_wait_loop:
+    ldrb r3, [r4,#6]
+    lsrs r3, r3, #8
+    bcc cmd_wait_loop
+
+    ldr r3, [r1, #0x10]
+    blx r6 // dstt_readSdDma_waitDataReady_address
+
+    // previous push had r2 = dma channel, r3 = dst at top of stack
+    // pop to the correct register for miiCardDmaCopy32
+    pop {r0, r2}
+    adds r1, #0x10 // Source. r1 is 0x04100000 from the calling function
+    movs r3, #1
+    lsls r3, r3, #9 // (1 << 9) = 512 = count
+
+    blx r7 // dstt_readSdDma_miiCardDmaCopy32Ptr
+
+cmd81_poll_dma:
+    // read sd fifo
+    // 81 xx xx xx xx xx xx xx
+    // xx bytes are leftover from previous command
+    movs r1, #0x81
+    strb r1, [r4,#0x8]
+
+    movs r1, #0xC0 // select rom mode, with irq
+    strb r1, [r4,#0x1]
+    movs r1, #0xA1
+    strb r1, [r4,#7]
+
+    pop {r4-r7,pc}
+
+.balign 4
+
+dstt_romSettings:
+    .word 0xA7180000
+
+.global dstt_readSdDma_applySectorCommand_address
+dstt_readSdDma_applySectorCommand_address:
+    .word 0
+
+.global dstt_readSdDma_stopTransmission_address
+dstt_readSdDma_stopTransmission_address:
+    .word 0
+
+.global dstt_readSdDma_waitDataReady_address
+dstt_readSdDma_waitDataReady_address:
+    .word 0
+
+.global dstt_readSdDma_miiCardDmaCopy32Ptr
+dstt_readSdDma_miiCardDmaCopy32Ptr:
+    .word 0
+
+.pool
+
+.end