diff options
Diffstat (limited to 'newlib/libc/machine/i960/strlen_ca.S')
| -rw-r--r-- | newlib/libc/machine/i960/strlen_ca.S | 146 |
1 files changed, 146 insertions, 0 deletions
diff --git a/newlib/libc/machine/i960/strlen_ca.S b/newlib/libc/machine/i960/strlen_ca.S new file mode 100644 index 0000000..350423b --- /dev/null +++ b/newlib/libc/machine/i960/strlen_ca.S @@ -0,0 +1,146 @@ +/******************************************************************************* + * + * Copyright (c) 1993 Intel Corporation + * + * Intel hereby grants you permission to copy, modify, and distribute this + * software and its documentation. Intel grants this permission provided + * that the above copyright notice appears in all copies and that both the + * copyright notice and this permission notice appear in supporting + * documentation. In addition, Intel grants this permission provided that + * you prominently mark as "not part of the original" any modifications + * made to this software or documentation, and that the name of Intel + * Corporation not be used in advertising or publicity pertaining to + * distribution of the software or the documentation without specific, + * written prior permission. + * + * Intel Corporation provides this AS IS, WITHOUT ANY WARRANTY, EXPRESS OR + * IMPLIED, INCLUDING, WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY + * OR FITNESS FOR A PARTICULAR PURPOSE. Intel makes no guarantee or + * representations regarding the use of, or the results of the use of, + * the software and documentation in terms of correctness, accuracy, + * reliability, currentness, or otherwise; and you rely on the software, + * documentation and results solely at your own risk. + * + * IN NO EVENT SHALL INTEL BE LIABLE FOR ANY LOSS OF USE, LOSS OF BUSINESS, + * LOSS OF PROFITS, INDIRECT, INCIDENTAL, SPECIAL OR CONSEQUENTIAL DAMAGES + * OF ANY KIND. IN NO EVENT SHALL INTEL'S TOTAL LIABILITY EXCEED THE SUM + * PAID TO INTEL FOR THE PRODUCT LICENSED HEREUNDER. + * + ******************************************************************************/ + + .file "strle_ca.s" +#ifdef __PIC + .pic +#endif +#ifdef __PID + .pid +#endif +/* + * (c) copyright 1988,1993 Intel Corp., all rights reserved + */ + +/* + procedure strlen (optimized assembler version for the CA) + + src_addr = strlen (src_addr) + + return the number of bytes that precede the null byte in the + string pointed to by src_addr. + + Undefined behavior will occur if the end of the source string (i.e. + the terminating null byte) is in the last four words of the program's + allocated memory space. This is so because, in several cases, strlen + will fetch ahead several words. Disallowing the fetch ahead would + impose a severe performance penalty. + + This program handles two cases: + + 1) the argument starts on a word boundary + 2) the argument doesn't start on a word boundary + + At the time of this writing, only g0 thru g7 and g13 are available + for use in this leafproc; other registers would have to be saved and + restored. These nine registers, plus tricky use of g14 are sufficient + to implement the routine. The registers are used as follows: + + g0 original src ptr; upon return it is the byte count. + g1 + g2 src ptr + g3 mask + g4 even word of the source string + g5 odd word of the source string + g6 copy of even word, shift count + g7 copy of odd word + g13 return address + g14 byte extracted. +*/ + + .globl _strlen + .globl __strlen + .leafproc _strlen, __strlen + .align 2 +_strlen: +#ifndef __PIC + lda Lrett,g14 +#else + lda Lrett-(.+8)(ip),g14 +#endif +__strlen: + + notand g0,3,g2 # extract word addr of start of src + lda (g14),g13 # preserve return address + and g0,3,g7 # extract byte offset of src + ld (g2),g5 # fetch word containing at least first byte + shlo 3,g7,g7 # get shift count for making mask for first word + lda 4(g2),g2 # post-increment src word pointer + subi 1,0,g3 # mask initially all ones + chkbit 2,g2 # are we on an even word boundary or an odd one? +#if __i960_BIG_ENDIAN__ + shro g7,g3,g3 # get mask for bytes needed from first word + notor g5,g3,g7 # set unneeded bytes to all ones + lda 0xff000000,g3 # byte extraction mask +#else + shlo g7,g3,g3 # get mask for bytes needed from first word + notor g5,g3,g7 # set unneeded bytes to all ones + lda 0xff,g3 # byte extraction mask +#endif + bno.f Lodd_word # branch if first word is odd + mov g7,g4 # move first word to copy thereof + ld (g2),g5 # load odd word + lda 4(g2),g2 # post-increment src word pointer + + +Leven_word: + scanbyte 0,g4 # check for null byte + movl g4,g6 # copy both words +Lodd_word: # trickery! if we branch here, following branch + /* instruction will fall thru, as we want, */ + /* effecting the load of g4 and g5 only. */ + ldl (g2),g4 # fetch next pair of word of src + bo.f Lsearch_for_null # branch if null found + scanbyte 0,g7 # check for null byte + lda 8(g2),g2 # post-increment src word pointer + bno.t Leven_word # branch if null not found yet + + subo 4,g2,g2 # back up the byte pointer + lda (g7),g6 # move odd word to search word +Lsearch_for_null: + subo 9,g2,g2 # back up the byte pointer +Lsearch_for_null.a: + and g6,g3,g14 # extract byte + cmpo 0,g14 # is it null? + lda 1(g2),g2 # bump src byte ptr +#if __i960_BIG_ENDIAN__ + shlo 8,g6,g6 # shift word to position next byte +#else + shro 8,g6,g6 # shift word to position next byte +#endif + bne.t Lsearch_for_null.a + +Lexit_code: + subo g0,g2,g0 # calculate string length + bx (g13) # g0 = addr of src; g14 = 0 +Lrett: + ret + +/* end of strlen */ |