Return to kldexpf.s CVS log

Up to [Net/2] / Net2 / arch / tahoe / math

Annotation of Net2/arch/tahoe/math/kldexpf.s, revision 1.1.1.1

1.1       root        1: /*-
                      2:  * Copyright (c) 1985 The Regents of the University of California.
                      3:  * All rights reserved.
                      4:  *
                      5:  * This code is derived from software contributed to Berkeley by
                      6:  * Computer Consoles Inc.
                      7:  *
                      8:  * Redistribution and use in source and binary forms, with or without
                      9:  * modification, are permitted provided that the following conditions
                     10:  * are met:
                     11:  * 1. Redistributions of source code must retain the above copyright
                     12:  *    notice, this list of conditions and the following disclaimer.
                     13:  * 2. Redistributions in binary form must reproduce the above copyright
                     14:  *    notice, this list of conditions and the following disclaimer in the
                     15:  *    documentation and/or other materials provided with the distribution.
                     16:  * 3. All advertising materials mentioning features or use of this software
                     17:  *    must display the following acknowledgement:
                     18:  *     This product includes software developed by the University of
                     19:  *     California, Berkeley and its contributors.
                     20:  * 4. Neither the name of the University nor the names of its contributors
                     21:  *    may be used to endorse or promote products derived from this software
                     22:  *    without specific prior written permission.
                     23:  *
                     24:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
                     25:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
                     26:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
                     27:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
                     28:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
                     29:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
                     30:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
                     31:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
                     32:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
                     33:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
                     34:  * SUCH DAMAGE.
                     35:  *
                     36:  *     @(#)Kldexpf.s   7.1 (Berkeley) 12/6/90
                     37:  */
                     38: 
                     39: #include "../tahoe/SYS.h"
                     40: #include "../math/fp.h"
                     41: #include "../math/Kfp.h"
                     42: 
                     43: /* @(*)Kldexpf.s       4.2 (Berkeley) 12/21/80
                     44:  *     Tahoe           2/2/83
                     45:  *
                     46:  * float Kldexpf (op_most, op_least, exp, hfs)
                     47:  *
                     48:  * Ldexp returns value*2**exp, if that result is in range.
                     49:  * If underflow occurs, it returns zero.  If overflow occurs,
                     50:  * it returns a value of appropriate sign and largest
                     51:  * possible magnitude.  In case of either overflow or underflow,
                     52:  * the external int "errno" is set to ERANGE.  Note that errno is
                     53:  * not modified if no error occurs, so if you intend to test it
                     54:  * after you use Kldexpf, you had better set it to something
                     55:  * other than ERANGE first (zero is a reasonable value to use).
                     56:  */
                     57: 
                     58:        .text
                     59: ENTRY(Kldexpf, R2)
                     60:        movl    4(fp),r0        /* Fetch "value" */
                     61:        movl    8(fp),r1
                     62: 
                     63:        andl3   $EXPMASK,r0,r2  /* r2 := shifted biased exponent */
                     64:        jeql    ld1             /* If it's zero, we're done */
                     65:        shar    $EXPSHIFT,r2,r2 /* shift to get value of exponent  */
                     66: 
                     67:        addl2   12(fp),r2       /* r2 := new biased exponent */
                     68:        jleq    under           /* if it's <= 0, we have an underflow */
                     69:        cmpl    r2,$256         /* Otherwise check if it's too big */
                     70:        jgeq    over            /* jump if overflow */
                     71: /*
                     72:  *     Construct the result and return
                     73:  */
                     74:        andl2   $0!EXPMASK,r0   /* clear old exponent */
                     75:        shal    $EXPSHIFT,r2,r2 /* Put the exponent back in the result */
                     76:        orl2    r2,r0
                     77: ld1:   ret
                     78: /*
                     79:  *     Underflow
                     80:  */
                     81: under: clrl    r0              /* Result is zero */
                     82:        clrl    r1
                     83:        orl2    $HFS_UNDF,*16(fp)
                     84:        jmp     err             /* Join general error code */
                     85: /*
                     86:  *     Overflow
                     87:  */
                     88: over:  movl    huge0,r0        /* Largest possible floating magnitude */
                     89:        movl    huge1,r1
                     90:        orl2    $HFS_OVF,*16(fp)
                     91:        orl2    $SIGNBIT,r0     /* If arg < 0, make result negative */
                     92: 
                     93: err:   orl2    $HFS_RANGE,*16(fp)      /* Indicate range error */
                     94:        ret
                     95: 
                     96:        .data
                     97: huge0: .long   0x7fffffff
                     98: huge1: .long   0xffffffff

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