Add software interface for reading SD card data

Adds functions to wait for data to be read, and to read data form the sd card controller.
2022-04-11 14:03:42 -05:00
parent 87d1457d94
commit f4e16c0c12
4 changed files with 29 additions and 0 deletions
--- a/sw/sd_card.s
+++ b/sw/sd_card.s
@@ -4,6 +4,8 @@

 .export _sd_card_command
 .export _sd_card_resp
+.export _sd_card_read_byte
+.export _sd_card_wait_for_data

 .autoimport on

@@ -33,6 +35,7 @@ _sd_card_resp:
        sta ptr1        ; store pointer
        stx ptr1+1
@1:     lda SD_CMD      ; wait for status flag
+        and #$01
        beq @1
        lda SD_ARG
        ldy #$0
@@ -48,3 +51,16 @@ _sd_card_resp:
        sta (ptr1),y
        ply
        rts
+
+_sd_card_read_byte:
+        lda SD_DATA
+        ldx #$00
+        rts
+
+_sd_card_wait_for_data:
+        pha
+@1:     lda SD_CMD      ; wait for status flag
+        and #$02
+        beq @1
+        pla
+        rts