| 301,3 → 301,44 |
|---|
| dst[end] = 0; |
| } |
| } |
| |
| |
| /* converts an ASCIIZ string into an unsigned short. returns 0 on success. */ |
| int atouns(unsigned short *r, const char *s) { |
| int err = 0; |
| |
| _asm { |
| mov si, s |
| xor ax, ax /* general purpose register */ |
| xor cx, cx /* contains the result */ |
| mov bx, 10 /* used as a multiplicative step */ |
| |
| NEXTBYTE: |
| xchg cx, ax /* move result into cx temporarily */ |
| lodsb /* AL = DS:[SI++] */ |
| /* is AL 0? if so we're done */ |
| test al, al |
| jz DONE |
| /* validate that AL is in range '0'-'9' */ |
| sub al, '0' |
| jc FAIL /* neg result */ |
| cmp al, 9 |
| jg FAIL |
| /* restore result into AX (CX contains the new digit) */ |
| xchg cx, ax |
| /* multiply result by 10 and add cl */ |
| mul bx /* DX AX = AX * BX(10) */ |
| jc FAIL /* overflow */ |
| add ax, cx |
| /* if CF then overflow occured (overflow part lands in DX) */ |
| jnc NEXTBYTE |
| |
| FAIL: |
| inc [err] |
| |
| DONE: /* save result (CX) into indirect memory address r */ |
| mov bx, [r] |
| mov [bx], cx |
| } |
| return(err); |
| } |