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authorThomas Martitz <kugel@rockbox.org>2010-05-06 21:04:40 +0000
committerThomas Martitz <kugel@rockbox.org>2010-05-06 21:04:40 +0000
commit50a6ca39ad4ed01922aa4f755f0ca579788226cf (patch)
treec7881b015b220558167310345b162324c96be15a /firmware/libc/strlen.c
parentadb506df14aded06ed6e9ebf8540e6fd383ffd6a (diff)
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Move c/h files implementing/defining standard library stuff into a new libc directory, also standard'ify some parts of the code base (almost entirely #include fixes).
This is to a) to cleanup firmware/common and firmware/include a bit, but also b) for Rockbox as an application which should use the host system's c library and headers, separating makes it easy to exclude our files from the build. git-svn-id: svn://svn.rockbox.org/rockbox/trunk@25850 a1c6a512-1295-4272-9138-f99709370657
Diffstat (limited to 'firmware/libc/strlen.c')
-rw-r--r--firmware/libc/strlen.c93
1 files changed, 93 insertions, 0 deletions
diff --git a/firmware/libc/strlen.c b/firmware/libc/strlen.c
new file mode 100644
index 0000000..4d33eaf
--- /dev/null
+++ b/firmware/libc/strlen.c
@@ -0,0 +1,93 @@
+/*
+FUNCTION
+ <<strlen>>---character string length
+
+INDEX
+ strlen
+
+ANSI_SYNOPSIS
+ #include <string.h>
+ size_t strlen(const char *<[str]>);
+
+TRAD_SYNOPSIS
+ #include <string.h>
+ size_t strlen(<[str]>)
+ char *<[src]>;
+
+DESCRIPTION
+ The <<strlen>> function works out the length of the string
+ starting at <<*<[str]>>> by counting chararacters until it
+ reaches a <<NULL>> character.
+
+RETURNS
+ <<strlen>> returns the character count.
+
+PORTABILITY
+<<strlen>> is ANSI C.
+
+<<strlen>> requires no supporting OS subroutines.
+
+QUICKREF
+ strlen ansi pure
+*/
+
+#include "config.h"
+#include <_ansi.h>
+#include <string.h>
+#include <limits.h>
+
+#define LBLOCKSIZE (sizeof (long))
+#define UNALIGNED(X) ((long)X & (LBLOCKSIZE - 1))
+
+#if LONG_MAX == 2147483647L
+#define DETECTNULL(X) (((X) - 0x01010101) & ~(X) & 0x80808080)
+#else
+#if LONG_MAX == 9223372036854775807L
+/* Nonzero if X (a long int) contains a NULL byte. */
+#define DETECTNULL(X) (((X) - 0x0101010101010101) & ~(X) & 0x8080808080808080)
+#else
+#error long int is not a 32bit or 64bit type.
+#endif
+#endif
+
+#ifndef DETECTNULL
+#error long int is not a 32bit or 64bit byte
+#endif
+
+size_t
+_DEFUN (strlen, (str),
+ _CONST char *str) ICODE_ATTR;
+
+size_t
+_DEFUN (strlen, (str),
+ _CONST char *str)
+{
+#if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)
+ _CONST char *start = str;
+
+ while (*str)
+ str++;
+
+ return str - start;
+#else
+ _CONST char *start = str;
+ unsigned long *aligned_addr;
+
+ if (!UNALIGNED (str))
+ {
+ /* If the string is word-aligned, we can check for the presence of
+ a null in each word-sized block. */
+ aligned_addr = (unsigned long*)str;
+ while (!DETECTNULL (*aligned_addr))
+ aligned_addr++;
+
+ /* Once a null is detected, we check each byte in that block for a
+ precise position of the null. */
+ str = (char*)aligned_addr;
+ }
+
+ while (*str)
+ str++;
+ return str - start;
+#endif /* not PREFER_SIZE_OVER_SPEED */
+}