50 lines
971 B
NASM
50 lines
971 B
NASM
; *** Const ***
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; Base of the Return Stack
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.equ RS_ADDR 0xf000
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; Number of bytes we keep as a padding between HERE and the scratchpad
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.equ PADDING 0x20
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; Offset of the code link relative to the beginning of the word
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.equ CODELINK_OFFSET 10
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; When set, the interpret should quit
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.equ FLAG_ENDPGM 1
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; *** Variables ***
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.equ INITIAL_SP FORTH_RAMSTART
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.equ CURRENT @+2
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.equ HERE @+2
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.equ INPUTPOS @+2
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.equ FLAGS @+2
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.equ FORTH_RAMEND @+1
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; *** Code ***
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MAIN:
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.dw compiledWord
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.dw INTERPRET+CODELINK_OFFSET
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.dw CHKEND
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; If FLAG_ENDPGM is set, stop the program, else, tweak the RS so that we loop.
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CHKEND:
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.dw nativeWord
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ld hl, FLAGS
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bit FLAG_ENDPGM, (hl)
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jr nz, .endpgm
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; not quitting, loop
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jr forthLoop
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.endpgm:
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ld sp, (INITIAL_SP)
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xor a
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ret
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forthMain:
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xor a
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ld (FLAGS), a
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ld (INITIAL_SP), sp
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ld hl, DOT ; last entry in hardcoded dict
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ld (CURRENT), hl
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ld hl, FORTH_RAMEND
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ld (HERE), hl
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forthLoop:
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ld ix, RS_ADDR
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ld iy, MAIN
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jp executeCodeLink
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