54328722ab
Adds a call that you can make to the BIOS to read sd blocks. Useful for the bootloader where there is not much space
55 lines
963 B
ArmAsm
55 lines
963 B
ArmAsm
.include "io.inc65"
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.export _irq_int, _nmi_int
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.importzp sreg, ptr1
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.segment "CODE"
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; IRQ
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_irq_int:
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jmp (irqmap,x)
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_nmi_int:
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rti
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irqmap:
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.addr handle_invalid
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.addr handle_sd_read
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handle_invalid:
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rti
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; sreg is the pointer to store the data
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; a/y is the block address
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; send command 17 with the block address of 00/y/a
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handle_sd_read:
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sta SD_ARG ; send command
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sty SD_ARG+1
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stz SD_ARG+2
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stz SD_ARG+3
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lda #$11
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sta SD_CMD
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@1: lda SD_CMD ; wait for status flag
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and #$01
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beq @1
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@2: lda SD_CMD ; wait for data
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and #$02
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beq @2
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ldy #$00
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@loop: lda SD_DATA ; copy first 256 bytes
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sta (sreg),y
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iny
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bne @loop
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ldy #$00 ; copy second 256 bytes
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inc sreg+1
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@loop2: lda SD_DATA
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sta (sreg),y
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iny
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bne @loop2
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rti |