55 lines
2.8 KiB
C
55 lines
2.8 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
|
|
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
|
|
╞══════════════════════════════════════════════════════════════════════════════╡
|
|
│ Copyright 2020 Justine Alexandra Roberts Tunney │
|
|
│ │
|
|
│ This program is free software; you can redistribute it and/or modify │
|
|
│ it under the terms of the GNU General Public License as published by │
|
|
│ the Free Software Foundation; version 2 of the License. │
|
|
│ │
|
|
│ This program is distributed in the hope that it will be useful, but │
|
|
│ WITHOUT ANY WARRANTY; without even the implied warranty of │
|
|
│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
|
|
│ General Public License for more details. │
|
|
│ │
|
|
│ You should have received a copy of the GNU General Public License │
|
|
│ along with this program; if not, write to the Free Software │
|
|
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
|
|
│ 02110-1301 USA │
|
|
╚─────────────────────────────────────────────────────────────────────────────*/
|
|
#include "libc/str/internal.h"
|
|
#include "libc/str/tpenc.h"
|
|
#include "libc/str/tpencode.h"
|
|
|
|
/**
|
|
* Thompson-Pike Varint Encoder.
|
|
*
|
|
* Implementation Details: The header macro should ensure this function
|
|
* is only called for non-ASCII, or DCE'd entirely. In addition to that
|
|
* this function makes a promise to not clobber any registers but %rax.
|
|
*
|
|
* @param p is what ch gets encoded to
|
|
* @param size is the number of bytes available in buf
|
|
* @param ch is a 32-bit integer
|
|
* @param awesome mode enables numbers the IETF unilaterally banned
|
|
* @return number of bytes written
|
|
* @note this encoding was designed on a napkin in a new jersey diner
|
|
*/
|
|
unsigned(tpencode)(char *p, size_t size, wint_t wc, bool32 awesome) {
|
|
int i, j;
|
|
unsigned long w;
|
|
if ((0 <= wc && wc < 32) && awesome && size >= 2) {
|
|
p[0] = 0xc0;
|
|
p[1] = 0x80;
|
|
p[1] |= wc;
|
|
return 2;
|
|
}
|
|
i = 0;
|
|
w = tpenc(wc);
|
|
do {
|
|
if (!size--) break;
|
|
p[i++] = w & 0xff;
|
|
} while (w >>= 8);
|
|
return i;
|
|
}
|