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https://opencores.org/ocsvn/forwardcom/forwardcom/trunk
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/forwardcom/libraries
- from Rev 119 to Rev 120
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Rev 119 → Rev 120
/atoi_light.as
0,0 → 1,77
/********************************* atoi_light.as ***************************** |
* Author: Agner Fog |
* date created: 2018-03-23 |
* Last modified: 2021-05-16 |
* Version: 1.11 |
* Project: ForwardCom library libc_light.li |
* Description: atoi: convert string to integer |
* This version is for CPUs with limited capabilities |
* C declaration: int64_t atoi(const char * str) |
* |
* Copyright 2018-2021 GNU General Public License http://www.gnu.org/licenses |
*****************************************************************************/ |
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code section execute align = 4 // code section |
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_atoi function public reguse = 3, 0 |
_atol function public reguse = 3, 0 |
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if (int64 r0 == 0) {jump EMPTYEND} // NULL pointer |
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int64 sp -= 3*8 // save r2 - r4 |
int64 [sp] = r2 |
int64 [sp+8] = r3 |
int64 [sp+0x10] = r4 |
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int r1 = 0 // state: 0: after whitespace |
// 1: after +/- |
// 2: after digit |
int64 r2 = 0 // value |
int r3 = 0 // sign |
int8 r4 = [r0] // read first character from string |
// loop through string until terminating zero |
while (int8+ r4 != 0) { |
if (uint8+ r4 <= ' ') { // whitespace |
if (int r1 != 0) {jump ERROREND} // space not allowed if state != 0. end of number |
jump NEXT // else |
} |
if (uint8+ r4 <= '-') { // '+' or '-' |
if (int r1 != 0) {jump ERROREND} // sign not allowed if state != 0. end of number |
int r1 = 1 // state = 1 |
if (uint8+ r4 == '-') { |
int8+ r3 = 1 // sign |
jump NEXT // else |
} |
if (uint8+ r4 != '+') { |
jump ERROREND // anything else than '+'. end of number |
} |
} |
else { |
int8+ r4 -= '0' // subtract ASCII '0' |
if (uint8+ r4 > 9) {jump ERROREND} // anything else than 0-9. end of number |
//int64 r2 *= 10 |
// multiply value by 10 without using mul instruction |
int64 r1 = r2 << 3 // value * 8 |
int64 r2 <<= 1 // value * 2 |
int64 r2 += r1 // value * 10 |
int64 r2 += r4 // + digit |
int r1 = 2 // state = 2 |
} |
NEXT: |
int64 r0++ // point to next character |
int8 r4 = [r0] // read next character from string |
} |
ERROREND: // jump here when a character that cannot be part of the string is met |
int64 r0 = r3 ? -r2 : r2 // change sign if r3 |
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int64 r2 = [sp] // restore r2 - r4 |
int64 r3 = [sp+8] |
int64 r4 = [sp+0x10] |
int64 sp += 3*8 |
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EMPTYEND: |
return |
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_atoi end |
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code end |