yangguangcai01 commented on code in PR #13180:
URL: https://github.com/apache/nuttx/pull/13180#discussion_r1806572740
##########
libs/libc/string/lib_memccpy.c:
##########
@@ -51,6 +81,71 @@
#undef memccpy /* See mm/README.txt */
FAR void *memccpy(FAR void *s1, FAR const void *s2, int c, size_t n)
{
+#ifdef CONFIG_LIBC_STRING_OPTIMIZE
+ FAR void *ptr = NULL;
+ FAR unsigned char *pout = (FAR unsigned char *)s1;
+ FAR const unsigned char *pin = (FAR const unsigned char *)s2;
+ FAR long *paligned_out;
+ FAR const long *paligned_in;
+ unsigned char endchar = c & 0xff;
+
+ /* If the size is small, or either pin or pout is unaligned,
+ * then punt into the byte copy loop. This should be rare.
+ */
+
+ if (!TOO_SMALL(n) && !UNALIGNED(pin, pout))
+ {
+ unsigned int i;
+ unsigned long mask = 0;
+
+ paligned_out = (FAR long *)pout;
+ paligned_in = (FAR long *)pin;
+
+ /* The fast code reads the ASCII one word at a time and only
+ * performs the bytewise search on word-sized segments if they
+ * contain the search character, which is detected by XORing
+ * the word-sized segment with a word-sized block of the search
+ * character and then detecting for the presence of NULL in the
+ * result.
+ */
+
+ for (i = 0; i < LITTLEBLOCKSIZE; i++)
+ {
+ mask = (mask << 8) + endchar;
+ }
+
+ /* Copy one long word at a time if possible. */
+
+ while (n >= LITTLEBLOCKSIZE)
+ {
+ unsigned long buffer = (unsigned long)(*paligned_in);
+ buffer ^= mask;
+ if (DETECTNULL(buffer))
+ {
+ break; /* endchar is found, go byte by byte from here */
+ }
+
+ *paligned_out++ = *paligned_in++;
+ n -= LITTLEBLOCKSIZE;
+ }
+
+ /* Pick up any residual with a byte copier. */
+
+ pout = (FAR unsigned char *)paligned_out;
+ pin = (FAR unsigned char *)paligned_in;
+ }
+
+ while (n--)
+ {
+ if ((*pout++ = *pin++) == endchar)
+ {
+ ptr = pout;
+ break;
+ }
+ }
+
+ return ptr;
+#else
Review Comment:
> i feel we should separate code with different license to separate files.
how do you think?
ok, I will separate these files.
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