64 lines
1.0 KiB
PHP
64 lines
1.0 KiB
PHP
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; make a char uppercase
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; IN al char
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; OUT al char
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; do nothing if >z
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ucase cmp al, 0x7B
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jnc .ret
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; do nothing if <a
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cmp al, 0x61
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jc .ret
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; do it!
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sub al, 0x20
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.ret ret
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; read integer from ascii string
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; default dec but allows 0x for hex
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; bogus result if larger than 16 bit
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; IN ds:si source string
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; cx max number of chars
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; OUT ax number
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; ds:si first rejected char
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; cx chars ignored
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lodnum xor di, di
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mov bx, 10
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cmp cx, 2
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jc .loop
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; test for 0x prefix
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mov ax, [si]
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cmp al, 0x30
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jne .loop
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mov al, ah
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call ucase
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cmp al, 0x58
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jne .loop
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; apply 0x prefix
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.hex add si, 2
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sub cx, 2
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mov bx, 0x10
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; check if there are chars left
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.loop test cx, cx
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jnz .do
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.ret mov ax, di
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ret
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.do mov al, [si]
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call ucase
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; check if in range
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sub al, 0x30
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jc .ret
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cmp al, 0x10
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jc .skip
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sub al, 7
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; must be smaller than base
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; necessary to prevent hex digits in decimals
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.skip mov ah, 0
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cmp ax, bx
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jnc .ret
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; mark as read
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inc si
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dec cx
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; add digit to number
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xchg ax, di
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mul bx
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add di, ax
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jmp .loop
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