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authorhpa <hpa>2004-11-10 22:31:50 +0000
committerhpa <hpa>2004-11-10 22:31:50 +0000
commit17f967640cef484f83d755c9dd016a946711236f (patch)
tree00bf0c0f2926cd6a9761eb372b55d090305aca44 /com32/lib/memmem.c
parentc67a2ac96611fa6aeb9ff3602c5e0c8265f1cc9d (diff)
downloadsyslinux-17f967640cef484f83d755c9dd016a946711236f.tar.gz
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Very first cut at a klibc-derived C library for com32
Diffstat (limited to 'com32/lib/memmem.c')
-rw-r--r--com32/lib/memmem.c44
1 files changed, 44 insertions, 0 deletions
diff --git a/com32/lib/memmem.c b/com32/lib/memmem.c
new file mode 100644
index 00000000..0f59938f
--- /dev/null
+++ b/com32/lib/memmem.c
@@ -0,0 +1,44 @@
+/*
+ * memmem.c
+ *
+ * Find a byte string inside a longer byte string
+ *
+ * This uses the "Not So Naive" algorithm, a very simple but
+ * usually effective algorithm, see:
+ *
+ * http://www-igm.univ-mlv.fr/~lecroq/string/
+ */
+
+#include <string.h>
+
+void *memmem(const void *haystack, size_t n, const void *needle, size_t m)
+{
+ const unsigned char *y = (const unsigned char *)haystack;
+ const unsigned char *x = (const unsigned char *)needle;
+
+ size_t j, k, l;
+
+ if ( m > n )
+ return NULL;
+
+ if ( x[0] == x[1] ) {
+ k = 2;
+ l = 1;
+ } else {
+ k = 1;
+ l = 2;
+ }
+
+ j = 0;
+ while ( j <= n-m ) {
+ if (x[1] != y[j+1]) {
+ j += k;
+ } else {
+ if ( !memcmp(x+2, y+j+2, m-2) && x[0] == y[j] )
+ return (void *)&y[j];
+ j += l;
+ }
+ }
+
+ return NULL;
+}