Return to strrchr.s CVS log

Up to [CSRG BSD Unix] / 43BSDReno / lib / libc / vax / string

Annotation of 43BSDReno/lib/libc/vax/string/strrchr.s, revision 1.1.1.1

1.1       root        1: /*
                      2:  * Copyright (c) 1988 Regents of the University of California.
                      3:  * All rights reserved.
                      4:  *
                      5:  * Redistribution and use in source and binary forms are permitted
                      6:  * provided that: (1) source distributions retain this entire copyright
                      7:  * notice and comment, and (2) distributions including binaries display
                      8:  * the following acknowledgement:  ``This product includes software
                      9:  * developed by the University of California, Berkeley and its contributors''
                     10:  * in the documentation or other materials provided with the distribution
                     11:  * and in all advertising materials mentioning features or use of this
                     12:  * software. Neither the name of the University nor the names of its
                     13:  * contributors may be used to endorse or promote products derived
                     14:  * from this software without specific prior written permission.
                     15:  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
                     16:  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
                     17:  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
                     18:  */
                     19: 
                     20: #if defined(LIBC_SCCS) && !defined(lint)
                     21:        .asciz "@(#)strrchr.s   5.4 (Berkeley) 6/1/90"
                     22: #endif /* LIBC_SCCS and not lint */
                     23: 
                     24: /*
                     25:  * Find the last occurence of c in the string cp.
                     26:  * Return pointer to match or null pointer.
                     27:  *
                     28:  * char *
                     29:  * strrchr(cp, c)
                     30:  *     char *cp, c;
                     31:  */
                     32: #include "DEFS.h"
                     33: 
                     34:        .lcomm  tbl,256
                     35: 
                     36: ENTRY(strrchr, 0)
                     37:        movzwl  $65535,r4       /* handy 65535 */
                     38:        movq    4(ap),r1        /* r1 = cp; r2 = c */
                     39:        movzbl  r2,r2
                     40:        beql    Lzero           /* special case for c == '\0' */
                     41: 
                     42:        clrl    r5              /* r5 = pointer to last match */
                     43: 
                     44: /*
                     45:  * Fancy scanc version.  Alas, it is not reentrant.
                     46:  */
                     47:        movab   tbl,r3          /* r3 = address of table */
                     48:        bbss    $0,(r3),Lreent  /* ensure not reentering */
                     49:        movab   (r3)[r2],r4
                     50:        incb    (r4)            /* mark both '\0' and c */
                     51: 0:
                     52:        scanc   $65535,(r1),(r3),$1     /* look for c or '\0' */
                     53:        beql    0b              /* keep looking */
                     54:        tstb    (r1)
                     55:        beql    1f              /* done if '\0' */
                     56:        movab   (r1)+,r5        /* save most recently found, and skip over it */
                     57:        jbr     0b              /* keep looking */
                     58: 1:
                     59:        movl    r5,r0           /* return last found (if any) */
                     60:        clrb    (r4)            /* clean up table */
                     61:        clrb    (r3)
                     62:        ret
                     63: 
                     64: /*
                     65:  * Special case for \0.
                     66:  */
                     67: Lzero:
                     68:        locc    $0,r4,(r1)      /* just find end of string */
                     69:        beql    Lzero           /* still looking */
                     70:        movl    r1,r0           /* found it */
                     71:        ret
                     72: 
                     73: /*
                     74:  * Slower reentrant version is two two-step searches.  The first
                     75:  * phase runs until we know where the string ends; it locates any
                     76:  * occurrences of c within a 65535-byte block.  Once we have found
                     77:  * the end of the string, we find any further occurrences before
                     78:  * that location.
                     79:  */
                     80: Lreent:
                     81: 0:     /* first phase */
                     82:        movl    r1,r3
                     83:        locc    $0,r4,(r3)      /* look for '\0' */
                     84:        bneq    1f
                     85:        locc    r2,r4,(r3)      /* continue phase 1 search for c */
                     86:        beql    0b
                     87:        movab   (r1)+,r5        /* found c: save and increment pointer */
                     88:        brb     0b              /* and continue */
                     89: 
                     90: 1:     /* second phase */
                     91:        subl3   r3,r1,r0        /* length of short block */
                     92:        movl    r3,r1
                     93: 2:
                     94:        locc    r2,r0,(r1)      /* look for c */
                     95:        beql    3f              /* skip if not found */
                     96:        movab   (r1)+,r5        /* save pointer as before */
                     97:        sobgtr  r0,2b           /* adjust count and loop */
                     98: 3:
                     99:        movl    r5,r0           /* return stashed pointer */
                    100:        ret

This archive runs on limited infrastructure. Preserving old code on modern bandwidth. Automated agents are requested to crawl responsibly.