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1.1 root 1: /*
2: * Copyright (c) 1986 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 are permitted
9: * provided that: (1) source distributions retain this entire copyright
10: * notice and comment, and (2) distributions including binaries display
11: * the following acknowledgement: ``This product includes software
12: * developed by the University of California, Berkeley and its contributors''
13: * in the documentation or other materials provided with the distribution
14: * and in all advertising materials mentioning features or use of this
15: * software. Neither the name of the University nor the names of its
16: * contributors may be used to endorse or promote products derived
17: * from this software without specific prior written permission.
18: * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
19: * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
20: * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
21: */
22:
23: #if defined(SYSLIBC_SCCS) && !defined(lint)
24: .asciz "@(#)muld.s 1.3 (Berkeley) 6/1/90"
25: #endif /* SYSLIBC_SCCS and not lint */
26:
27: #include <tahoemath/fp.h>
28: #include "DEFS.h"
29:
30: #define HIDDEN 23 /* here we count from 0 not from 1 as in fp.h */
31:
32: XENTRY(muld, R2|R3|R4|R5|R6|R7|R8|R9)
33: clrl r3 /* r3 - sign: 0 for positive,1 for negative. */
34: movl 4(fp),r0
35: jgeq 1f
36: movl $1,r3
37: 1: movl 12(fp),r2
38: jgeq 2f
39: bbc $0,r3,1f /* seconed operand is negative. */
40: clrl r3 /* if first was negative, make result positive. */
41: jmp 2f
42: 1: movl $1,r3 /* if first was positive, make result negative. */
43: 2: andl2 $EXPMASK,r0 /* compute first 'pure'exponent. */
44: jeql is_res1
45: shrl $EXPSHIFT,r0,r0
46: subl2 $BIASP1,r0
47: andl2 $EXPMASK,r2 /* compute seconed 'pure'exponent. */
48: jeql is_res2
49: shrl $EXPSHIFT,r2,r2
50: subl2 $BIASP1,r2
51: addl2 r0,r2 /* add the exponents. */
52: addl2 $(BIASP1+2),r2
53: jleq underflow
54: cmpl r2,$258 /* normalization can make the exp. smaller. */
55: jgeq overflow
56: /*
57: * We have the sign in r3,the exponent in r2,now is the time to
58: * perform the multiplication...
59: */
60: /* fetch first fraction: (r0,r1) */
61: andl3 $(0!(EXPMASK | SIGNBIT)),4(fp),r0
62: orl2 $(0!CLEARHID),r0
63: movl 8(fp),r1
64: shlq $7,r0,r0 /* leave the sign bit cleared. */
65:
66: /* fetch seconed fraction: (r4,r5) */
67: andl3 $(0!(EXPMASK | SIGNBIT)),12(fp),r4
68: orl2 $(0!CLEARHID),r4
69: movl 16(fp),r5
70: shlq $7,r4,r4 /* leave the sign bit cleared. */
71:
72: /* in the following lp1 stands for least significant part of operand 1,
73: * lp2 for least significant part of operand 2,
74: * mp1 for most significant part of operand 1,
75: * mp2 for most significant part of operand 2.
76: */
77:
78: clrl r6
79: shrl $1,r1,r1 /* clear the sign bit of the lp1. */
80: jeql 1f
81: emul r1,r4,$0,r6 /* r6,r7 <-- lp1*mp2 */
82: shlq $1,r6,r6 /* to compensate for the shift we did to clear the sign bit. */
83: 1: shrl $1,r5,r5 /* clear the sign bit of the lp2. */
84: jeql 1f
85: emul r0,r5,$0,r8 /* r8,r9 <-- mp1*lp2 */
86: shlq $1,r8,r8
87: addl2 r9,r7 /* r6,r7 <-- the sum of the products. */
88: adwc r8,r6
89: 1: emul r0,r4,$0,r0 /* r0,r1 <-- mp1*mp2 */
90: addl2 r6,r1 /* add the most sig. part of the sum. */
91: adwc $0,r0
92: movl r0,r4 /* to see how much we realy need to shift. */
93: movl $6,r5 /* r5 - shift counter. */
94: shrl $7,r4,r4 /* dummy shift. */
95: 1: bbs $HIDDEN,r4,realshift
96: shll $1,r4,r4
97: decl r2 /* update exponent. */
98: jeql underflow
99: decl r5 /* update shift counter. */
100: jmp 1b
101: realshift:
102: shrq r5,r0,r0
103: bbc $0,r1,shiftmore
104: incl r1 /* rounding. */
105: shiftmore:
106: shrq $1,r0,r0
107: comb:
108: andl2 $CLEARHID,r0
109: shll $EXPSHIFT,r2,r4
110: orl2 r4,r0
111: cmpl r2,$256
112: jlss 1f
113: callf $4,fpover
114: sign:
115: 1: bbc $0,r3,done
116: orl2 $SIGNBIT,r0
117: done: ret
118:
119:
120:
121: is_res1:
122: bbc $31,4(fp),retzero
123: callf $4,fpresop
124: ret
125: is_res2:
126: bbc $31,12(fp),retzero
127: callf $4,fpresop
128: ret
129: retzero:
130: clrl r0
131: clrl r1
132: ret
133: overflow:
134: callf $4,fpover
135: jmp sign
136: underflow:
137: callf $4,fpunder
138: ret
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