mirror of
https://github.com/jart/cosmopolitan.git
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8da931a7f6
This program popped up on Hacker News recently. It's the only modern compiler I've ever seen that doesn't have dependencies and is easily modified. So I added all of the missing GNU extensions I like to use which means it might be possible soon to build on non-Linux and have third party not vendor gcc binaries.
116 lines
3.9 KiB
C
116 lines
3.9 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ This program is free software; you can redistribute it and/or modify │
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│ it under the terms of the GNU General Public License as published by │
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│ the Free Software Foundation; version 2 of the License. │
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│ │
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│ This program is distributed in the hope that it will be useful, but │
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│ WITHOUT ANY WARRANTY; without even the implied warranty of │
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│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
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│ General Public License for more details. │
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│ │
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│ You should have received a copy of the GNU General Public License │
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│ along with this program; if not, write to the Free Software │
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│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
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│ 02110-1301 USA │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/conv/conv.h"
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#include "libc/limits.h"
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#include "libc/nexgen32e/bsr.h"
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#include "libc/str/str.h"
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/**
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* Decodes 128-bit signed integer from ASCII string.
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*
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* @param s is a non-NULL NUL-terminated string
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* @param endptr if non-NULL will always receive a pointer to the char
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* following the last one this function processed, which is usually
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* the NUL byte, or in the case of invalid strings, would point to
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* the first invalid character
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* @param base can be anywhere between [2,36] or 0 to auto-detect based
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* on the the prefixes 0 (octal), 0x (hexadecimal), 0b (binary), or
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* decimal (base 10) by default.
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* @return the decoded saturated number
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* @see strtoumax
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*/
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intmax_t strtoimax(const char *s, char **endptr, int base) {
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bool neg;
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uintmax_t x;
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intmax_t res;
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unsigned diglet, bits;
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x = 0;
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bits = 0;
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neg = false;
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while (isspace(*s)) {
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s++;
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}
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switch (*s) {
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case '-':
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neg = true;
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/* 𝑠𝑙𝑖𝑑𝑒 */
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case '+':
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s++;
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break;
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default:
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break;
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}
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if (!(2 <= base && base <= 36)) {
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if (*s == '0') {
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s++;
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if (*s == 'x' || *s == 'X') {
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s++;
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base = 16;
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} else if (*s == 'b' || *s == 'B') {
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s++;
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base = 2;
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} else {
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base = 8;
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}
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} else {
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base = 10;
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}
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} else if (*s == '0') {
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++s;
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if (base == 2 && *s == 'b' && *s == 'B') ++s;
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if (base == 16 && *s == 'x' && *s == 'X') ++s;
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}
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for (;;) {
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diglet = kBase36[*s & 0xff];
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if (!diglet || diglet > base) break;
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diglet -= 1;
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if (!diglet || !x || (bits = bsr(diglet) + bsrmax(x)) < 127) {
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s++;
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x *= base;
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x += diglet;
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} else if (neg) {
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if (bits == 127) {
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x *= base;
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x += diglet;
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if (x == INTMAX_MIN) s++;
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}
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x = INTMAX_MIN;
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break;
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} else {
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x = INTMAX_MAX;
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break;
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}
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}
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if (endptr) *endptr = s;
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if (neg) {
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res = -x;
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} else {
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res = x;
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}
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return res;
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}
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