aboutsummaryrefslogtreecommitdiff
path: root/git2d/utf8.h
diff options
context:
space:
mode:
Diffstat (limited to 'git2d/utf8.h')
-rw-r--r--git2d/utf8.h74
1 files changed, 0 insertions, 74 deletions
diff --git a/git2d/utf8.h b/git2d/utf8.h
deleted file mode 100644
index 56c6285..0000000
--- a/git2d/utf8.h
+++ /dev/null
@@ -1,74 +0,0 @@
-/*-
- * SPDX-License-Identifier: Unlicense
- * SPDX-FileContributor: Chris Wellons <wellons@nullprogram.com>
- *
- * From: https://nullprogram.com/blog/2017/10/06/
- */
-
-#ifndef UTF8_H
-#define UTF8_H
-
-#include <stdint.h>
-
-/*
- * Decode the next character, C, from BUF, reporting errors in E.
- *
- * Since this is a branchless decoder, four bytes will be read from the
- * buffer regardless of the actual length of the next character. This
- * means the buffer _must_ have at least three bytes of zero padding
- * following the end of the data stream.
- *
- * Errors are reported in E, which will be non-zero if the parsed
- * character was somehow invalid: invalid byte sequence, non-canonical
- * encoding, or a surrogate half.
- *
- * The function returns a pointer to the next character. When an error
- * occurs, this pointer will be a guess that depends on the particular
- * error, but it will always advance at least one byte.
- */
-inline void *
-utf8_decode(void *buf, uint32_t *c, int *e)
-{
- static const char lengths[] = {
- 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
- 0, 0, 0, 0, 0, 0, 0, 0, 2, 2, 2, 2, 3, 3, 4, 0
- };
- static const int masks[] = {0x00, 0x7f, 0x1f, 0x0f, 0x07};
- static const uint32_t mins[] = {4194304, 0, 128, 2048, 65536};
- static const int shiftc[] = {0, 18, 12, 6, 0};
- static const int shifte[] = {0, 6, 4, 2, 0};
-
- uint8_t *s = buf;
- int len = lengths[s[0] >> 3];
-
- /*
- * Compute the pointer to the next character early so that the next
- * iteration can start working on the next character. Neither Clang
- * nor GCC figure out this reordering on their own.
- */
- uint8_t *next = s + len + !len;
-
- /*
- * Assume a four-byte character and load four bytes. Unused bits are
- * shifted out.
- */
- *c = (uint32_t)(s[0] & masks[len]) << 18;
- *c |= (uint32_t)(s[1] & 0x3f) << 12;
- *c |= (uint32_t)(s[2] & 0x3f) << 6;
- *c |= (uint32_t)(s[3] & 0x3f) << 0;
- *c >>= shiftc[len];
-
- /* Accumulate the various error conditions. */
- *e = (*c < mins[len]) << 6; /* non-canonical encoding */
- *e |= ((*c >> 11) == 0x1b) << 7; /* surrogate half? */
- *e |= (*c > 0x10FFFF) << 8; /* out of range? */
- *e |= (s[1] & 0xc0) >> 2;
- *e |= (s[2] & 0xc0) >> 4;
- *e |= (s[3] ) >> 6;
- *e ^= 0x2a; /* top two bits of each tail byte correct? */
- *e >>= shifte[len];
-
- return next;
-}
-
-#endif