Rename boot to bios, add sd call

Adds a call that you can make to the BIOS to read sd blocks. Useful for the bootloader where there is not much space
2022-04-18 20:24:29 -05:00
parent 64f6f0b397
commit 54328722ab
10 changed files with 72 additions and 9 deletions
--- a/sw/bios/devices/interrupt.s
+++ b/sw/bios/devices/interrupt.s
@@ -0,0 +1,55 @@
+.include "io.inc65"
+
+.export   _irq_int, _nmi_int
+
+.importzp sreg, ptr1
+
+.segment  "CODE"
+
+; IRQ
+_irq_int:
+        jmp (irqmap,x)
+
+_nmi_int:
+        rti
+
+irqmap:
+        .addr handle_invalid
+        .addr handle_sd_read
+
+handle_invalid:
+        rti
+
+; sreg is the pointer to store the data
+; a/y is the block address
+; send command 17 with the block address of 00/y/a
+handle_sd_read:
+        sta SD_ARG          ; send command
+        sty SD_ARG+1
+        stz SD_ARG+2
+        stz SD_ARG+3
+        lda #$11
+        sta SD_CMD
+
+@1:     lda SD_CMD          ; wait for status flag
+        and #$01
+        beq @1
+
+@2:     lda SD_CMD          ; wait for data
+        and #$02
+        beq @2
+
+        ldy #$00
+@loop:  lda SD_DATA         ; copy first 256 bytes
+        sta (sreg),y
+        iny
+        bne @loop
+
+        ldy #$00            ; copy second 256 bytes
+        inc sreg+1
+@loop2: lda SD_DATA
+        sta (sreg),y
+        iny
+        bne @loop2
+
+        rti