40 lines
702 B
NASM
40 lines
702 B
NASM
.db MAX_MEM 0xFFFF
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.db VIDEO_MEM 0xF37F
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.db MAX_LENGTH MAX_MEM - MAX_LENGTH
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.db MSG "Hello, World!", 0
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_start:
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copy r1, MSG ; Pointer into r1
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copy r8, VIDEO_MEM
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call strlen
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copy r1, MSG
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cmp r2, 0
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je _end
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cmp r2, MAX_LENGTH
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jg _end
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draw_loop:
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copy byte [r8], [r1]
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inc r1
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inc r8
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dec r2
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cmp r2, 0
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je _end
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jmp draw_loop
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_end:
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jmp _end
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; Returns the length of a NULL terminated string
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; Arguments: R1 - Pointer to the string
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; Returns: R2 - Contains the length of the string
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strlen:
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copy r2, 0 ; length
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cmp [r1], 0
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je end ;The string is zero length
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loop:
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inc r1
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cmp [r1], 0
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je end
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inc r2
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jmp loop
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end:
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ret |