commit 25f5a5d8e5b1f22986782bfa72a779fc215dfefb
parent 6538c57c130b7b9406b9b8a87950132b6af2a645
Author: benjamin paul <bpaul@bpaul.xyz>
Date: Sun, 8 Aug 2021 12:36:19 +1000
OMG this made an improvement in the perf -e instructions:u test!!
Diffstat:
| M | src/main.c | | | 39 | ++++++++++++++++++++++++++++++++++++++- |
1 file changed, 38 insertions(+), 1 deletion(-)
diff --git a/src/main.c b/src/main.c
@@ -5,7 +5,44 @@
#define VERSION "v0.0.1"
/* sizeof magically gets the length of the string! (plus \0) */
-#define CMD(s) strncmp(buf, s, sizeof(s)-1) == 0
+#define CMD(s) new_strncmp(buf, s, sizeof(s)-1) == 0
+
+/* A modified version of the strncmp code which is somehow faster */
+bool
+new_strncmp(const char *s1, const char *s2, unsigned long n) {
+ int i;
+
+ char c[4];
+
+ if (n >= 4) {
+ unsigned long n4 = n >> 2;
+ do {
+ for (i = 0; i < 4; i++) {
+ c[i] = s1[i] - s2[i];
+ if (s1[i] == '\0' || c[i] != 0) {
+ return c[i];
+ }
+ }
+
+ s1+=4;
+ s2+=4;
+
+ n4--;
+ } while (n4 > 0);
+ n &= 3;
+ }
+
+ while (n > 0) {
+ c[0] = *s1 - *s2;
+ if (*s1 == '\0' || c[0] != 0) {
+ return c[0];
+ }
+ s1++;
+ s2++;
+ }
+
+ return c[0];
+}
int
main() {
