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

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

@@ -0,0 +1,73 @@
+.cpu arm7tdmi
+.syntax unified
+.thumb
+
+.section "dstt_sdstoptransmission", "ax"
+.global dstt_sdStopTransmission
+.type dstt_sdStopTransmission, %function
+dstt_sdStopTransmission:
+    // send SD_CMD12_STOP_TRANSMISSION
+    push {r3-r6,lr}
+
+    ldr r3, =0xA7180000
+    ldr r4, =0x040001A0
+
+    // select rom mode, without irq
+    // the caller may not have ensured this is set
+    movs r6, #0x80
+    strb r6, [r4,#1]
+
+    // set sd host mode DSTT_MODE_SDCMD_RESPONSE_32BIT, SD_CMD12_STOP_TRANSMISSION
+    // 51 00 00 00 00 0C 01 00
+    movs r5, #0x51
+    str r5, [r4,#0x8]
+    ldr r5,= 0x00010C00
+    str r5, [r4,#0xC]
+    str r3, [r4,#0x4]
+
+    movs r6, #0x41
+    lsls r6, r6, #20 // r6 = 0x04100000
+
+cmd51_1_wait_loop:
+    ldrb r5, [r4,#6]
+    lsrs r5, r5, #8
+    bcc cmd51_1_wait_loop
+    ldr r5, [r6, #0x10]
+
+    // sd busy poll
+    // 50 xx xx xx xx xx xx xx
+    // xx bytes are leftover from previous command
+    movs r5, #0x50
+    strb r5, [r4,#0x8]
+
+cmd50_poll_loop:
+    str r3, [r4,#4]
+
+cmd50_wait_loop:
+    ldrb r5, [r4,#6]
+    lsrs r5, r5, #8
+    bcc cmd50_wait_loop
+    ldr r5, [r6, #0x10]
+    cmp r5, #0
+    bne cmd50_poll_loop
+
+    // read sd response
+    // 52 xx xx xx xx xx xx xx
+    // xx bytes are leftover from previous command
+    movs r5, #0x52
+    strb r5, [r4,#0x8]
+    str r3, [r4,#4]
+
+cmd52_wait_loop:
+    ldrb r5, [r4,#6]
+    lsrs r5, r5, #8
+    bcc cmd52_wait_loop
+    ldr r5, [r6, #0x10]
+
+    pop {r3-r6,pc}
+
+.balign 4
+
+.pool
+
+.end