82 lines
1.4 KiB
PHP
82 lines
1.4 KiB
PHP
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; --- Data Stack --- ;
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; on this channel we love garth wilson: https://wilsonminesco.com/stacks/StackOps.ASM
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; data stack is built up of 2-byte cells
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; TODO: this is broken, jumping here does nothing to the stack and skips several instructions, could be an emulator problem tho
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; push_lit: ; this bad boy lets you inline a literal (low byte first) right after `jsr push_lit` and put it on the stack, once again, on this channel we love garth wilson
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; push2
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; phx
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; tsx
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; txa
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; tay
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; plx
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; lda $102, y
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; sta 0, x
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; clc
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; adc #2
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; sta $102, y
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; lda $103, y
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; sta 1, x
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; adc #0
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; sta $103, y
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; fetch:
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; lda (0, x)
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; pha
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; inc 0, x
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; bne .1
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; inc 1, x
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; .1:
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; lda (0, x)
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; bra put
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; push
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; put:
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; sta 1, x
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; pla
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; sta 0, x
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; rts
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plus: ; add: (n1 n2 -- n1+n2)
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clc
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lda 0, x
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adc 2, x
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sta 2, x
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lda 1, x
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adc 3, x
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sta 3, x
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pop
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rts
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mult: ; multiply: (n1 n2 -- n1*n2), frankly, i don't know how this works, but TODO: will try to figure it out later
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phy
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stz n
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ldy #0
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.1:
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lsr 3, x
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ror 2, x
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bcc .2
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clc
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lda n
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adc 0, x
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sta n
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tya
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adc 1, x
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tay
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.2:
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asl 0, x
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rol 1, x
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lda 2, x
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ora 3, x
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bne .1
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lda n
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sta 2, x
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sty 3, x
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pop
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ply
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rts
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