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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 "@(#)divd.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(divd, 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 $BIAS,r0
47: andl2 $EXPMASK,r2 # compute seconed 'pure'exponent.
48: jeql is_res2
49: shrl $EXPSHIFT,r2,r2
50: subl2 $BIAS,r2
51: subl3 r2,r0,r2 # subtruct the exponents.
52: addl2 $BIAS,r2
53: jleq underf
54: # normalization can make the exp. smaller.
55: #
56: # We have the sign in r3,the exponent in r2,now is the time to
57: # perform the division...
58: #
59: # fetch dividend. (r4,r5)
60: andl3 $(0!(EXPMASK | SIGNBIT)),4(fp),r4
61: orl2 $(0!CLEARHID),r4
62: movl 8(fp),r5
63:
64: # fetch divisor : (r6,r7)
65: andl3 $(0!(EXPMASK | SIGNBIT)),12(fp),r6
66: orl2 $(0!CLEARHID),r6
67: movl 16(fp),r7
68:
69: movl $0,r0 # init r0,r1 to be zeros
70: movl $0,r1
71: movl $(0!CLEARHID),r8# r8 first bit to set (if).
72: shll $1,r8,r8 # to have one more bit,because we might
73: # have to shift left to normelize.
74: movl $0,r9
75:
76: 2:
77: subl2 r7,r5
78: sbwc r6,r4
79: jgeq 1f
80: addl2 r7,r5
81: adwc r6,r4
82: shlq $1,r4,r4
83: shrq $1,r8,r8
84: jeql over
85: jmp 2b
86: 1:
87: orl2 r8,r0
88: orl2 r9,r1
89: shlq $1,r4,r4
90: shrq $1,r8,r8
91: jneq 2b
92:
93: over:
94: callf $4,fnorm
95: sign:
96: 1: bbc $0,r3,done
97: orl2 $SIGNBIT,r0
98: done: ret
99:
100: is_res1:
101: bbc $31,4(fp),retz
102: callf $4,fpresop
103: ret
104: is_res2:
105: bbc $31,12(fp),z_div
106: callf $4,fpresop
107: ret
108: retz:
109: clrl r0
110: clrl r1
111: ret
112: underf:
113: callf $4,fpunder
114: ret
115: z_div:
116: callf $4,fpzdiv
117: ret
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