Mercurial > ecos
diff packages/language/c/libc/string/current/src/memcmp.cxx @ 115:6ed91473a1cd ecos-sw-2000-08-21
Merge from eCos master repository on 2000-08-21-22:40:54-BST
| author | jlarmour |
|---|---|
| date | Fri, 25 Aug 2000 17:32:38 +0000 |
| parents | |
| children | 4c750ce71ae3 |
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new file mode 100644 --- /dev/null +++ b/packages/language/c/libc/string/current/src/memcmp.cxx @@ -0,0 +1,176 @@ +//=========================================================================== +// +// memcmp.cxx +// +// ANSI standard memcmp() routine +// +//=========================================================================== +//####COPYRIGHTBEGIN#### +// +// ------------------------------------------- +// The contents of this file are subject to the Red Hat eCos Public License +// Version 1.1 (the "License"); you may not use this file except in +// compliance with the License. You may obtain a copy of the License at +// http://www.redhat.com/ +// +// Software distributed under the License is distributed on an "AS IS" +// basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the +// License for the specific language governing rights and limitations under +// the License. +// +// The Original Code is eCos - Embedded Configurable Operating System, +// released September 30, 1998. +// +// The Initial Developer of the Original Code is Red Hat. +// Portions created by Red Hat are +// Copyright (C) 1998, 1999, 2000 Red Hat, Inc. +// All Rights Reserved. +// ------------------------------------------- +// +//####COPYRIGHTEND#### +//=========================================================================== +//#####DESCRIPTIONBEGIN#### +// +// Author(s): jlarmour +// Contributors: +// Date: 2000-04-14 +// Purpose: +// Description: +// Usage: +// +//####DESCRIPTIONEND#### +// +//=========================================================================== + +// CONFIGURATION + +#include <pkgconf/libc_string.h> // Configuration header + +// INCLUDES + +#include <cyg/infra/cyg_type.h> // Common type definitions +#include <cyg/infra/cyg_trac.h> // Tracing support +#include <cyg/infra/cyg_ass.h> // Assertion support +#include <string.h> // Header for this file +#include <stddef.h> // Compiler definitions such as size_t, NULL etc. +#include <cyg/libc/string/stringsupp.hxx> // Useful string function support and + // prototypes + + +// EXPORTED SYMBOLS + +externC int +memcmp( const void *s1, const void *s2, size_t n ) \ + CYGBLD_ATTRIB_WEAK_ALIAS(__memcmp); + +// FUNCTIONS + +int +__memcmp( const void *s1, const void *s2, size_t n ) +{ + int retval; + + CYG_REPORT_FUNCNAMETYPE( "__memcmp", "returning %d" ); + CYG_REPORT_FUNCARG3( "s1=%08x, s2=%08x, n=%d", s1, s2, n ); + + CYG_CHECK_DATA_PTR( s1, "s1 is not a valid pointer!" ); + CYG_CHECK_DATA_PTR( s2, "s2 is not a valid pointer!" ); + +#if defined(CYGIMP_LIBC_STRING_PREFER_SMALL_TO_FAST) || defined(__OPTIMIZE_SIZE__) + const unsigned char *m1 = (const unsigned char *) s1; + const unsigned char *m2 = (const unsigned char *) s2; + + while (n--) + { + if (*m1 != *m2) + { + retval = *m1 - *m2; + CYG_REPORT_RETVAL( retval ); + return retval; + } + m1++; + m2++; + } + CYG_REPORT_RETVAL( 0 ); + return 0; +#else + const unsigned char *m1 = (const unsigned char *) s1; + const unsigned char *m2 = (const unsigned char *) s2; + const CYG_WORD *aligned_m1; + const CYG_WORD *aligned_m2; + + // If the size is too small, or either pointer is unaligned, + // then we punt to the byte compare loop. Hopefully this will + // not turn up in inner loops. + if (CYG_LIBC_STR_OPT_TOO_SMALL(n) || CYG_LIBC_STR_UNALIGNED2(m1,m2)) + { + while (n--) + { + if (*m1 != *m2) + { + retval = *m1 - *m2; + CYG_REPORT_RETVAL( retval ); + return retval; + } + m1++; + m2++; + } + CYG_REPORT_RETVAL( 0 ); + return 0; + } + + // Otherwise, load and compare the blocks of memory one + // word at a time. + aligned_m1 = (const CYG_WORD *) m1; + aligned_m2 = (const CYG_WORD *) m2; + while (n > CYG_LIBC_STR_OPT_LITTLEBLOCKSIZE) + { + if (*aligned_m1 != *aligned_m2) + { + // This block of characters has a mismatch, somewhere. + // xoring them together and then testing for null would + // be fastest, but this is clearer code. + m1 = (const unsigned char *)aligned_m1; + m2 = (const unsigned char *)aligned_m2; + while (n--) + { + if (*m1 != *m2) + { + retval = *m1 - *m2; + CYG_REPORT_RETVAL( retval ); + return retval; + } + m1++; + m2++; + } + // NOT REACHED + } + aligned_m1++; + aligned_m2++; + n -= CYG_LIBC_STR_OPT_LITTLEBLOCKSIZE; + } + + // checking the last few characters + + m1 = (const unsigned char *)aligned_m1; + m2 = (const unsigned char *)aligned_m2; + + while (n--) + { + if (*m1 != *m2) + { + retval = *m1 - *m2; + CYG_REPORT_RETVAL( retval ); + return retval; + } + m1++; + m2++; + } + + CYG_REPORT_RETVAL( 0 ); + return 0; +#endif // not defined(CYGIMP_LIBC_STRING_PREFER_SMALL_TO_FAST) || + // defined(__OPTIMIZE_SIZE__) +} // __memcmp() + +// EOF memcmp.cxx
