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/*
* This file is part of LibCSS.
* Licensed under the MIT License,
* http://www.opensource.org/licenses/mit-license.php
* Copyright 2007-9 John-Mark Bell <jmb@netsurf-browser.org>
*/
#include "utils/utils.h"
css_fixed number_from_lwc_string(lwc_string *string,
bool int_only, size_t *consumed)
{
size_t len;
const uint8_t *ptr;
int sign = 1;
int32_t intpart = 0;
int32_t fracpart = 0;
int32_t pwr = 1;
if (string == NULL || lwc_string_length(string) == 0 || consumed == NULL)
return 0;
len = lwc_string_length(string);
ptr = (uint8_t *)lwc_string_data(string);
/* number = [+-]? ([0-9]+ | [0-9]* '.' [0-9]+) */
/* Extract sign, if any */
if (ptr[0] == '-') {
sign = -1;
len--;
ptr++;
} else if (ptr[0] == '+') {
len--;
ptr++;
}
/* Ensure we have either a digit or a '.' followed by a digit */
if (len == 0) {
*consumed = 0;
return 0;
} else {
if (ptr[0] == '.') {
if (len == 1 || ptr[1] < '0' || '9' < ptr[1]) {
*consumed = 0;
return 0;
}
} else if (ptr[0] < '0' || '9' < ptr[0]) {
*consumed = 0;
return 0;
}
}
/* Now extract intpart, assuming base 10 */
while (len > 0) {
/* Stop on first non-digit */
if (ptr[0] < '0' || '9' < ptr[0])
break;
/* Prevent overflow of 'intpart'; proper clamping below */
if (intpart < (1 << 22)) {
intpart *= 10;
intpart += ptr[0] - '0';
}
ptr++;
len--;
}
/* And fracpart, again, assuming base 10 */
if (int_only == false && len > 1 && ptr[0] == '.' &&
('0' <= ptr[1] && ptr[1] <= '9')) {
ptr++;
len--;
while (len > 0) {
if (ptr[0] < '0' || '9' < ptr[0])
break;
if (pwr < 1000000) {
pwr *= 10;
fracpart *= 10;
fracpart += ptr[0] - '0';
}
ptr++;
len--;
}
fracpart = ((1 << 10) * fracpart + pwr/2) / pwr;
if (fracpart >= (1 << 10)) {
intpart++;
fracpart &= (1 << 10) - 1;
}
}
*consumed = (char *)ptr - lwc_string_data(string);
if (sign > 0) {
/* If the result is larger than we can represent,
* then clamp to the maximum value we can store. */
if (intpart >= (1 << 21)) {
intpart = (1 << 21) - 1;
fracpart = (1 << 10) - 1;
}
}
else {
/* If the negated result is smaller than we can represent
* then clamp to the minimum value we can store. */
if (intpart >= (1 << 21)) {
intpart = -(1 << 21);
fracpart = 0;
}
else {
intpart = -intpart;
if (fracpart) {
fracpart = (1 << 10) - fracpart;
intpart--;
}
}
}
return (intpart << 10) | fracpart;
}
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