Add loop unrolling to bring the profilable mem* functions closer to

newlib, because memset is called a LOT in the course of RSA signing, and
we need to understand how much time we're actually spending there.

1 files changed, 127 insertions, 0 deletions

diff --git a/libraries/libprof/memfunc.c b/libraries/libprof/memfunc.c
new file mode 100644
index 0000000..fc908e1
--- /dev/null
+++ b/libraries/libprof/memfunc.c
@@ -0,0 +1,127 @@
+#include <stdint.h>
+#include <string.h>
+
+/*
+ * Profilable substitutes for mem*(), lacking libc_p.a
+ *
+ * This code was written with reference to newlib, and was recently
+ * brought closer into line with newlib, to make profiling more accurate.
+ *
+ * Newlib is maintained by Cygwin, which is Red Hat. There is no copyright
+ * statement in the corresponding newlib source files, nor is there a
+ * COPYING file in newlib/libc/string or newlib/libc. Consider this file
+ * to be covered under one or more of the 50 copyright notices in
+ * newlib/COPYING, most of which are BSD. In any case, this file is only
+ * used for profiling, and is not used in production builds.
+ */
+
+#define is_word_aligned(x) (((size_t)(x) & 3) == 0)
+
+void *memcpy(void *dst, const void *src, size_t n)
+{
+    uint8_t *d8 = (uint8_t *)dst;
+    uint8_t *s8 = (uint8_t *)src;
+
+    if (n >= sizeof(uint32_t) && is_word_aligned(src) && is_word_aligned(dst)) {
+        uint32_t *d32 = (uint32_t *)dst;
+        uint32_t *s32 = (uint32_t *)src;
+        while (n >= 4 * sizeof(uint32_t)) {
+            *d32++ = *s32++;
+            *d32++ = *s32++;
+            *d32++ = *s32++;
+            *d32++ = *s32++;
+            n -= 4 * sizeof(uint32_t);
+        }
+        while (n >= sizeof(uint32_t)) {
+            *d32++ = *s32++;
+            n -= sizeof(uint32_t);
+        }
+        d8 = (uint8_t *)d32;
+        s8 = (uint8_t *)s32;
+    }
+    while (n-- > 0) {
+        *d8++ = *s8++;
+    }
+
+    return dst;
+}
+
+void *memset(void *dst, int c, size_t n)
+{
+    uint8_t *d8 = (uint8_t *)dst;
+    uint8_t c8 = (uint8_t)c;
+
+    while (!is_word_aligned(d8)) {
+        if (n--)
+            *d8++ = c8;
+        else
+            return dst;
+    }
+    if (n >= sizeof(uint32_t)) {
+        uint32_t *d32 = (uint32_t *)d8;
+        uint32_t c32 = (c8 << 24) | (c8 << 16) | (c8 << 8) | (c8);
+        while (n >= 4 * sizeof(uint32_t)) {
+            *d32++ = c32;
+            *d32++ = c32;
+            *d32++ = c32;
+            *d32++ = c32;
+            n -= 4 * sizeof(uint32_t);
+        }
+        while (n >= sizeof(uint32_t)) {
+            *d32++ = c32;
+            n -= sizeof(uint32_t);
+        }
+        d8 = (uint8_t *)d32;
+    }
+    while (n-- > 0) {
+        *d8++ = c8;
+    }
+
+    return dst;
+}
+
+int memcmp(const void *dst, const void *src, size_t n)
+{
+    uint8_t *d8 = (uint8_t *)dst;
+    uint8_t *s8 = (uint8_t *)src;
+
+    if (n >= sizeof(uint32_t) && is_word_aligned(src) && is_word_aligned(dst)) {
+        uint32_t *d32 = (uint32_t *)dst;
+        uint32_t *s32 = (uint32_t *)src;
+        while (n >= sizeof(uint32_t)) {
+            if (*d32 != *s32)
+                break;
+            d32++;
+            s32++;
+            n -= sizeof(uint32_t);
+        }
+        d8 = (uint8_t *)d32;
+        s8 = (uint8_t *)s32;
+    }
+    while (n-- > 0) {
+        if (*d8 != *s8)
+            return (*d8 - *s8);
+        d8++;
+        s8++;
+    }
+
+    return 0;
+}
+
+void *memmove(void *dst, const void *src, size_t n)
+{
+    uint8_t *d8 = (uint8_t *)dst;
+    uint8_t *s8 = (uint8_t *)src;
+
+    if ((s8 < d8) && (d8 < s8 + n)) {
+        /* Destructive overlap...have to copy backwards */
+        s8 += n;
+        d8 += n;
+        while (n-- > 0) {
+            *--d8 = *--s8;
+	}
+        return dst;
+    }
+
+    return memcpy(dst, src, n);
+}