[libc] Rewrite string functions

Some of the C library string functions have an unknown provenance.
Reimplement all such functions to avoid potential licensing
uncertainty.

Remove the inline-assembler versions of strlen(), memswap(), and
strncmp(); these save a minimal amount of space (around 40 bytes in
total) and are not performance-critical.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

2 files changed, 97 insertions, 42 deletions

diff --git a/src/include/string.h b/src/include/string.h
index dfd78a69..59696dd8 100644
--- a/src/include/string.h
+++ b/src/include/string.h
@@ -1,46 +1,53 @@
-/*
- *  Copyright (C) 1991, 1992  Linus Torvalds
- *  Copyright (C) 2004 Tobias Lorenz
+#ifndef _STRING_H
+#define _STRING_H
+
+/** @file
  *
- *  string handling functions
- *  based on linux/include/linux/ctype.h
- *       and linux/include/linux/string.h
+ * String functions
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
  */
 
-FILE_LICENCE ( GPL2_ONLY );
-
-#ifndef ETHERBOOT_STRING_H
-#define ETHERBOOT_STRING_H
+FILE_LICENCE ( GPL2_OR_LATER );
 
 #include <stddef.h>
 #include <bits/string.h>
 
-char * strcpy(char * dest,const char *src) __nonnull;
-char * strncpy(char * dest,const char *src,size_t count) __nonnull;
-char * strcat(char * dest, const char * src) __nonnull;
-int __pure strcmp(const char * cs,const char * ct) __nonnull;
-int __pure strncmp(const char * cs,const char * ct,
-				     size_t count) __nonnull;
-char * __pure strchr(const char * s, int c) __nonnull;
-char * __pure strrchr(const char * s, int c) __nonnull;
-size_t __pure strlen(const char * s) __nonnull;
-size_t __pure strnlen(const char * s, size_t count) __nonnull;
-char * __pure strpbrk(const char * cs,const char * ct) __nonnull;
-char * strsep(char **s, const char *ct) __nonnull;
-void * memset(void * s,int c,size_t count) __nonnull;
+/* Architecture-specific code is expected to provide these functions,
+ * but may instead explicitly choose to use the generic versions.
+ */
+void * memset ( void *dest, int character, size_t len ) __nonnull;
 void * memcpy ( void *dest, const void *src, size_t len ) __nonnull;
-void * memmove(void * dest,const void *src,size_t count) __nonnull;
-int __pure memcmp(const void * cs,const void * ct,
-				    size_t count) __nonnull;
-char * __pure strstr(const char * s1,const char * s2) __nonnull;
-void * __pure memchr(const void *s, int c, size_t n) __nonnull;
-char * __malloc strdup(const char *s) __nonnull;
-char * __malloc strndup(const char *s, size_t n) __nonnull;
+void * memmove ( void *dest, const void *src, size_t len ) __nonnull;
+extern void * generic_memset ( void *dest, int character,
+			       size_t len ) __nonnull;
+extern void * generic_memcpy ( void *dest, const void *src,
+			       size_t len ) __nonnull;
+extern void * generic_memmove ( void *dest, const void *src,
+				size_t len ) __nonnull;
+
+extern int __pure memcmp ( const void *first, const void *second,
+			   size_t len ) __nonnull;
+extern void * __pure memchr ( const void *src, int character,
+			      size_t len ) __nonnull;
+extern void * memswap ( void *dest, void *src, size_t len ) __nonnull;
+extern int __pure strcmp ( const char *first, const char *second ) __nonnull;
+extern int __pure strncmp ( const char *first, const char *second,
+			    size_t max ) __nonnull;
+extern size_t __pure strlen ( const char *src ) __nonnull;
+extern size_t __pure strnlen ( const char *src, size_t max ) __nonnull;
+extern char * __pure strchr ( const char *src, int character ) __nonnull;
+extern char * __pure strrchr ( const char *src, int character ) __nonnull;
+extern char * __pure strstr ( const char *haystack,
+			      const char *needle ) __nonnull;
+extern char * strcpy ( char *dest, const char *src ) __nonnull;
+extern char * strncpy ( char *dest, const char *src, size_t max ) __nonnull;
+extern char * strcat ( char *dest, const char *src ) __nonnull;
+extern char * __malloc strdup ( const char *src ) __nonnull;
+extern char * __malloc strndup ( const char *src, size_t max ) __nonnull;
+extern char * __pure strpbrk ( const char *string,
+			       const char *delim ) __nonnull;
+extern char * strsep ( char **string, const char *delim ) __nonnull;
 
-extern const char * __pure strerror ( int errno );
+extern char * __pure strerror ( int errno );
 
-#endif /* ETHERBOOT_STRING */
+#endif /* _STRING_H */
diff --git a/src/include/strings.h b/src/include/strings.h
index 6912a1e4..8b57a40a 100644
--- a/src/include/strings.h
+++ b/src/include/strings.h
@@ -1,12 +1,23 @@
 #ifndef _STRINGS_H
 #define _STRINGS_H
 
+/** @file
+ *
+ * String functions
+ *
+ */
+
 FILE_LICENCE ( GPL2_OR_LATER );
 
-#include <limits.h>
 #include <string.h>
 #include <bits/strings.h>
 
+/**
+ * Find last (i.e. most significant) set bit
+ *
+ * @v x			Value
+ * @ret msb		Most significant bit set in value (LSB=1), or zero
+ */
 static inline __attribute__ (( always_inline )) int
 __constant_flsll ( unsigned long long x ) {
 	int r = 0;
@@ -41,6 +52,12 @@ __constant_flsll ( unsigned long long x ) {
 	return r;
 }
 
+/**
+ * Find last (i.e. most significant) set bit
+ *
+ * @v x			Value
+ * @ret msb		Most significant bit set in value (LSB=1), or zero
+ */
 static inline __attribute__ (( always_inline )) int
 __constant_flsl ( unsigned long x ) {
 	return __constant_flsll ( x );
@@ -49,24 +66,55 @@ __constant_flsl ( unsigned long x ) {
 int __flsll ( long long x );
 int __flsl ( long x );
 
+/**
+ * Find last (i.e. most significant) set bit
+ *
+ * @v x			Value
+ * @ret msb		Most significant bit set in value (LSB=1), or zero
+ */
 #define flsll( x ) \
 	( __builtin_constant_p ( x ) ? __constant_flsll ( x ) : __flsll ( x ) )
 
+/**
+ * Find last (i.e. most significant) set bit
+ *
+ * @v x			Value
+ * @ret msb		Most significant bit set in value (LSB=1), or zero
+ */
 #define flsl( x ) \
 	( __builtin_constant_p ( x ) ? __constant_flsl ( x ) : __flsl ( x ) )
 
+/**
+ * Find last (i.e. most significant) set bit
+ *
+ * @v x			Value
+ * @ret msb		Most significant bit set in value (LSB=1), or zero
+ */
 #define fls( x ) flsl ( x )
 
-extern int strcasecmp ( const char *s1, const char *s2 );
-
+/**
+ * Copy memory
+ *
+ * @v src		Source
+ * @v dest		Destination
+ * @v len		Length
+ */
 static inline __attribute__ (( always_inline )) void
-bcopy ( const void *src, void *dest, size_t n ) {
-	memmove ( dest, src, n );
+bcopy ( const void *src, void *dest, size_t len ) {
+	memmove ( dest, src, len );
 }
 
+/**
+ * Zero memory
+ *
+ * @v dest		Destination
+ * @v len		Length
+ */
 static inline __attribute__ (( always_inline )) void
-bzero ( void *s, size_t n ) {
-	memset ( s, 0, n );
+bzero ( void *dest, size_t len ) {
+	memset ( dest, 0, len );
 }
 
+int __pure strcasecmp ( const char *first, const char *second ) __nonnull;
+
 #endif /* _STRINGS_H */