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Apply some touchups

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This commit is contained in:
Justine Tunney 2021-02-07 06:11:44 -08:00
parent 9f149e1de3
commit 2f3bd90216
139 changed files with 1188 additions and 1154 deletions
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60
libc/str/memmem.c
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@ -16,42 +16,8 @@
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/macros.h"
#include "libc/mem/alloca.h"
#include "libc/str/str.h"
static void KnuthMorrisPrattInit(ssize_t m, ssize_t *T, const char *W) {
ssize_t i = 2;
ssize_t j = 0;
T[0] = -1;
T[1] = 0;
while (i < m) {
if (W[i - 1] == W[j]) {
T[i++] = j++ + 1;
} else if (j > 0) {
j = T[j];
} else {
T[i++] = 0;
}
}
T[m] = 0;
}
static size_t KnuthMorrisPratt(long m, const long *T, const char *W, long n,
const char *S) {
long i = 0, j = 0;
while (i + j < n) {
if (W[i] == S[i + j]) {
i++;
if (i == m) break;
} else {
j = j + i - T[i];
if (i > 0) i = T[i];
}
}
return j;
}
/**
* Searches for fixed-length substring in memory region.
*
@ -61,24 +27,16 @@ static size_t KnuthMorrisPratt(long m, const long *T, const char *W, long n,
* @param needlelen is its character count
* @return pointer to first result or NULL if not found
*/
void *memmem(const void *haystackp, size_t haystacklen, const void *needlep,
void *memmem(const void *haystack, size_t haystacklen, const void *needle,
size_t needlelen) {
long *T;
size_t i;
const char *haystack, *needle, *h;
needle = needlep;
haystack = haystackp;
if (needlelen > haystacklen) return NULL;
size_t i, j;
if (!needlelen) return haystack;
h = memchr(haystack, *needle, haystacklen);
if (!h || needlelen == 1) return h;
haystacklen -= h - haystack;
if (needlelen < haystacklen && memcmp(h, needle, needlelen) == 0) {
return h;
} else {
T = alloca((needlelen + 1) * sizeof(long));
KnuthMorrisPrattInit(needlelen, T, needle);
i = KnuthMorrisPratt(needlelen, T, needle, haystacklen, h);
return i < haystacklen ? h + i : NULL;
for (i = 0; i < haystacklen; ++i) {
for (j = 0;; ++j) {
if (j == needlelen) return (/*unconst*/ char *)haystack + i;
if (i + j == haystacklen) break;
if (((char *)needle)[j] != ((char *)haystack)[i + j]) break;
}
}
return NULL;
}