80 lines
3.4 KiB
C
80 lines
3.4 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/fmt/conv.h"
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#include "libc/intrin/packsswb.h"
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#include "libc/intrin/pandn.h"
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#include "libc/intrin/pcmpgtw.h"
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#include "libc/intrin/pmovmskb.h"
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#include "libc/str/str.h"
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#include "libc/str/tpenc.h"
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#include "libc/str/utf16.h"
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static const int16_t kDel16[8] = {127, 127, 127, 127, 127, 127, 127, 127};
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/**
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* Transcodes UTF-16 to UTF-8.
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*
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* @param dst is output buffer
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* @param dstsize is bytes in dst
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* @param src is NUL-terminated UTF-16 input string
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* @return ax bytes written excluding nul
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* @return dx index of character after nul word in src
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*/
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axdx_t tprecode16to8(char *dst, size_t dstsize, const char16_t *src) {
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axdx_t r;
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uint64_t w;
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wint_t x, y;
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int16_t v1[8], v2[8], v3[8], vz[8];
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r.ax = 0;
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r.dx = 0;
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for (;;) {
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if (!IsTiny() && !((uintptr_t)(src + r.dx) & 15)) {
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/* 10x speedup for ascii */
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memset(vz, 0, 16);
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while (r.ax + 8 < dstsize) {
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memcpy(v1, src + r.dx, 16);
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pcmpgtw(v2, v1, vz);
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pcmpgtw(v3, v1, kDel16);
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pandn((void *)v2, (void *)v3, (void *)v2);
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if (pmovmskb((void *)v2) != 0xFFFF) break;
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packsswb((void *)v1, v1, v1);
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memcpy(dst + r.ax, v1, 8);
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r.ax += 8;
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r.dx += 8;
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}
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}
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if (!(x = src[r.dx++])) break;
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if (IsUtf16Cont(x)) continue;
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if (!IsUcs2(x)) {
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if (!(y = src[r.dx++])) break;
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x = MergeUtf16(x, y);
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}
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w = tpenc(x);
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while (w && r.ax + 1 < dstsize) {
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dst[r.ax++] = w & 0xFF;
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w >>= 8;
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}
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}
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if (r.ax < dstsize) {
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dst[r.ax] = 0;
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}
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return r;
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}
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