28 lines
615 B
NASM
28 lines
615 B
NASM
.db video_start 0xF37F
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.db msg "Hello, world!", 0
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load r1, [msg] ; Because the lod* instructions can't load an address
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; from anything but a register, this becomes laa r1, [msg]
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;Routine: string_length
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;In: String address in r1
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;Out: Length in R2
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string_length:
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loadb r3, [r1] ; Load the byte from the address in R1, into R3
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load r2, 0 ; String length
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cmp r3, 0 ; Is R3 a null byte?
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je end
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inc r2
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start:
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inc r1 ; next char
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loadb r3, [r1] ; Load the next character byte into R3
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cmpi r3, 0 ; Null byte?
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je end
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inc r2 ; Nope, increment the length counter
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jmp start
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end:
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ret
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