f3c7ac9696
Instead of using the bootsector to load a bootloader, just put the bootloader in the ROM and call it a day. It looks for a file on the SD card in the root directory named `kernel.bin` and loads it into memory. This is not a perfect solution, as the kernel will grow larger and the kernel load address will have to change. At this point I could add back the bootloader, but that is for later. Also the bootloader is just a copy of the kernel, so that can be trimmed down a lot.
71 lines
1.3 KiB
ArmAsm
71 lines
1.3 KiB
ArmAsm
.include "io.inc65"
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.importzp sp, sreg
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.export _hex_set_8
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.export _hex_set_16
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.export _hex_set_24
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.export _hex_enable
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.export _sw_read
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.export _led_set
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.autoimport on
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.code
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; @in A: idx Stack[0]: val
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; @out A: 0 for success, 1 for failure.
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; Sets one of the 3 pairs of hex digits.
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_hex_set_8:
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phx
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cmp #$3 ; If idx >= 3 then fail
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bcc @1
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plx
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lda #$1
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rts
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@1: tax ; Move idx into x
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jsr popa ; put val into a
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sta SEVEN_SEG,x ; write to val
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lda #$0
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plx
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rts
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; @in A/X: val
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; @out A: 0 for success, 1 for failure
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; Sets the low 2 pairs of hex digits
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_hex_set_16:
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sta SEVEN_SEG
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stx SEVEN_SEG+1
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lda #$0
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rts
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; @in A/X/sreg: val
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; @out A: 0 for success, 1 for failure
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; Sets the 3 pairs of hex digits for a 24 bit value
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_hex_set_24:
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sta SEVEN_SEG
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stx SEVEN_SEG+1
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lda sreg
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sta SEVEN_SEG+2
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lda #$0
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rts
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; @in A: mask
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; Set the mask for seven seg enables
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_hex_enable:
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sta SEVEN_SEG+3
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rts
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; @out A: The Value of the switches
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; Reads the current values of the switches.
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_sw_read:
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lda SW
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ldx #$0
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rts
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; @in A: val
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; @out A: 0 for success, 1 for failure
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; Sets the LEDs
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_led_set:
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sta LED
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rts |