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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: * @(#)Kmulf.s 7.1 (Berkeley) 12/6/90
37: */
38:
39: #include "../math/fp.h"
40: #include "../math/Kfp.h"
41: #include "../tahoe/SYS.h"
42:
43: #define HIDDEN 23 /* here we count from 0 not from 1 as in fp.h */
44:
45: /*
46: * _Kmulf(acc_most,acc_least,op_most,op_least,hfs)
47: */
48: .text
49: ENTRY(Kmulf, R5|R4|R3|R2)
50: clrl r3 /* r3 - sign: 0 for positive,1 for negative. */
51: movl 4(fp),r0
52: jgeq 1f
53: movl $1,r3
54: 1: movl 12(fp),r2
55: jgeq 2f
56: bbc $0,r3,1f /* seconed operand is negative. */
57: clrl r3 /* if first was negative, make result positive. */
58: jmp 2f
59: 1: movl $1,r3 /* if first was positive, make result negative. */
60: 2: andl2 $EXPMASK,r0 /* compute first 'pure'exponent. */
61: jeql retzero
62: shrl $EXPSHIFT,r0,r0
63: subl2 $BIASP1,r0
64: andl2 $EXPMASK,r2 /* compute seconed 'pure'exponent. */
65: jeql retzero
66: shrl $EXPSHIFT,r2,r2
67: subl2 $BIASP1,r2
68: addl2 r0,r2 /* add the exponents. */
69: addl2 $(BIASP1+2),r2
70: jleq underflow
71: cmpl r2,$258 /* normalization can make the exp. smaller. */
72: jgeq overflow
73: /*
74: * We have the sign in r3,the exponent in r2,now is the time to
75: * perform the multiplication...
76: */
77: /* fetch first fraction: (r0) */
78: andl3 $(0!(EXPMASK | SIGNBIT)),4(fp),r0
79: orl2 $(0!CLEARHID),r0
80: shll $7,r0,r0 /* leave the sign bit cleared. */
81:
82: /* fetch seconed fraction: (r4) */
83: andl3 $(0!(EXPMASK | SIGNBIT)),12(fp),r4
84: orl2 $(0!CLEARHID),r4
85: shll $7,r4,r4 /* leave the sign bit cleared. */
86:
87:
88: emul r4,r0,$0,r0
89: movl r0,r4 /* to see how much we realy need to shift. */
90: movl $6,r5 /* r5 - shift counter. */
91: shrl $7,r4,r4 /* dummy shift. */
92: 1: bbs $HIDDEN,r4,realshift
93: shll $1,r4,r4
94: decl r2 /* update exponent. */
95: jeql underflow
96: decl r5 /* update shift counter. */
97: jmp 1b
98: realshift:
99: shrl r5,r0,r0
100: bbc $0,r1,shiftmore
101: incl r1 /* rounding. */
102: shiftmore:
103: shrl $1,r0,r0
104: comb:
105: andl2 $CLEARHID,r0
106: shll $EXPSHIFT,r2,r4
107: orl2 r4,r0
108: cmpl r2,$256
109: jlss 1f
110: orl2 $HFS_OVF,*20(fp)
111: sign:
112: 1: bbc $0,r3,done
113: orl2 $SIGNBIT,r0
114: done: ret
115:
116:
117:
118: retzero:
119: clrl r0
120: ret
121: overflow:
122: orl2 $HFS_OVF,*20(fp)
123: jmp sign
124: underflow:
125: orl2 $HFS_UNDF,*20(fp)
126: ret
127:
128:
129:
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