feat(newlib): riscv: add CONFIG_LIBC_OPTIMIZED_MISALIGNED_ACCESS config option

This option replaces implementations of functions from ROM: - memcpy - memcmp - memmove - str[n]cpy - str[n]cmp The functions used in the firmware will be better optimized for misaligned memory. Here are some measurements in CPU cycles for 4096-byte buffers: memcpy: 28676 -> 4128 memcmp: 49147 -> 14259 memmove: 33896 -> 8086 strcpy: 32771 -> 17313 strcmp: 32775 -> 13191
2025-03-26 15:18:54 +07:00
parent f3625b0fb0
commit ec68cb3300
46 changed files with 1049 additions and 58 deletions
@@ -0,0 +1,63 @@
+/*
+ * SPDX-FileCopyrightText: 1994-2009 Red Hat, Inc.
+ *
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD AND Apache-2.0
+ *
+ * SPDX-FileContributor: 2025 Espressif Systems (Shanghai) CO LTD
+ */
+#include <string.h>
+#include <limits.h>
+#include "local.h"
+
+__attribute__((optimize("-Os")))
+int
+strncmp(const char *s1,
+        const char *s2,
+        size_t n)
+{
+    unsigned long *a1;
+    unsigned long *a2;
+
+    if (n == 0) {
+        return 0;
+    }
+
+    /* If s1 or s2 are unaligned, then compare bytes. */
+    if (!UNALIGNED_X_Y(s1, s2)) {
+        /* If s1 and s2 are word-aligned, compare them a word at a time. */
+        a1 = (unsigned long*)s1;
+        a2 = (unsigned long*)s2;
+        while (n >= sizeof(long) && *a1 == *a2) {
+            n -= sizeof(long);
+
+            /* If we've run out of bytes or hit a null, return zero
+            since we already know *a1 == *a2.  */
+            if (n == 0 || DETECT_NULL(*a1)) {
+                return 0;
+            }
+
+            a1++;
+            a2++;
+        }
+
+        /* A difference was detected in last few bytes of s1, so search bytewise */
+        s1 = (char*)a1;
+        s2 = (char*)a2;
+    }
+
+    while (n-- > 0 && *s1 == *s2) {
+        /* If we've run out of bytes or hit a null, return zero
+        since we already know *s1 == *s2.  */
+        if (n == 0 || *s1 == '\0') {
+            return 0;
+        }
+        s1++;
+        s2++;
+    }
+    return (*(unsigned char *) s1) - (*(unsigned char *) s2);
+}
+
+// Hook to force the linker to include this file
+void esp_libc_include_strncmp_impl(void)
+{
+}