tsiry-sandratraina.com
A modern Music Player Daemon based on Rockbox open source high quality audio player
libadwaita
audio
rust
zig
deno
mpris
rockbox
mpd
1/*
2FUNCTION
3 <<strlen>>---character string length
4
5INDEX
6 strlen
7
8ANSI_SYNOPSIS
9 #include <string.h>
10 size_t strlen(const char *<[str]>);
11
12TRAD_SYNOPSIS
13 #include <string.h>
14 size_t strlen(<[str]>)
15 char *<[src]>;
16
17DESCRIPTION
18 The <<strlen>> function works out the length of the string
19 starting at <<*<[str]>>> by counting chararacters until it
20 reaches a <<NULL>> character.
21
22RETURNS
23 <<strlen>> returns the character count.
24
25PORTABILITY
26<<strlen>> is ANSI C.
27
28<<strlen>> requires no supporting OS subroutines.
29
30QUICKREF
31 strlen ansi pure
32*/
33
34#include "config.h"
35#include "_ansi.h"
36#include <string.h>
37#include <limits.h>
38
39#define LBLOCKSIZE (sizeof (long))
40#define ROCKBOX_UNALIGNED(X) ((long)X & (LBLOCKSIZE - 1))
41
42#if LONG_MAX == 2147483647L
43#define DETECTNULL(X) (((X) - 0x01010101) & ~(X) & 0x80808080)
44#else
45#if LONG_MAX == 9223372036854775807L
46/* Nonzero if X (a long int) contains a NULL byte. */
47#define DETECTNULL(X) (((X) - 0x0101010101010101) & ~(X) & 0x8080808080808080)
48#else
49#error long int is not a 32bit or 64bit type.
50#endif
51#endif
52
53#ifndef DETECTNULL
54#error long int is not a 32bit or 64bit byte
55#endif
56
57size_t
58_DEFUN (strlen, (str),
59 _CONST char *str) ICODE_ATTR;
60
61size_t
62_DEFUN (strlen, (str),
63 _CONST char *str)
64{
65#if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)
66 _CONST char *start = str;
67
68 while (*str)
69 str++;
70
71 return str - start;
72#else
73 _CONST char *start = str;
74 unsigned long *aligned_addr;
75
76 if (!ROCKBOX_UNALIGNED (str))
77 {
78 /* If the string is word-aligned, we can check for the presence of
79 a null in each word-sized block. */
80 aligned_addr = (unsigned long*)str;
81 while (!DETECTNULL (*aligned_addr))
82 aligned_addr++;
83
84 /* Once a null is detected, we check each byte in that block for a
85 precise position of the null. */
86 str = (char*)aligned_addr;
87 }
88
89 while (*str)
90 str++;
91 return str - start;
92#endif /* not PREFER_SIZE_OVER_SPEED */
93}