URL
https://opencores.org/ocsvn/forwardcom/forwardcom/trunk
Subversion Repositories forwardcom
[/] [forwardcom/] [libraries/] [atoi.as] - Rev 132
Go to most recent revision | Compare with Previous | Blame | View Log
/********************************* atoi.as ***********************************
* Author: Agner Fog
* date created: 2018-03-23
* Last modified: 2021-05-16
* Version: 1.11
* Project: ForwardCom library libc.li
* Description: atoi: convert string to integer
* C declaration: int64_t atoi(const char * str)
*
* Copyright 2018-2021 GNU General Public License http://www.gnu.org/licenses
*****************************************************************************/
code section execute align = 4 // code section
_atoi function public reguse = 3, 0
if (int64 r0 == 0) {jump EMPTYEND} // NULL pointer
push(r2, 4) // save r2 - r4
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 // 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
pop(r2, 4) // restore r2 - r4
EMPTYEND:
return
_atoi end
code end
Go to most recent revision | Compare with Previous | Blame | View Log