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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 "@(#)addd.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: XENTRY(addd, R2|R3|R4|R5|R6|R7|R8|R9|R10)
31: /*
32: * see which operand has a greater exponent
33: * The greater one will be fetched into r0,r1,r2,r3.
34: * r0,r1 - 'pure' fraction, r2 - exponent, r3 - sign).
35: * The smaller operand will be fetched into r4,r5,r6,r7.
36: */
37: andl3 $EXPMASK,4(fp),r0
38: andl3 $EXPMASK,12(fp),r1
39: cmpl r0,r1
40: jgtr first_greater
41:
42: movl 12(fp),r0 # bigger operand to r0,r1
43: movl 16(fp),r1
44:
45: movl 4(fp),r4 # smaller operand to r4,r5
46: movl 8(fp),r5
47: jmp expo
48:
49: first_greater:
50: movl 4(fp),r0 # bigger operand to r0,r1
51: movl 8(fp),r1
52:
53: movl 12(fp),r4 # smaller operand to r4,r5
54: movl 16(fp),r5
55:
56: /*
57: * compute exponents:
58: */
59: expo:
60: andl3 $EXPMASK,r0,r2 # r2 will hold the exponent.
61: jeql is_res1 # check for reserved operand.
62: shrl $EXPSHIFT,r2,r2
63:
64:
65: andl3 $EXPMASK,r4,r6 # r6 will hold the exponent.
66: jeql is_res2 # check for reserved operand.
67: shrl $EXPSHIFT,r6,r6
68: /*
69: * compare the exponents:
70: */
71: subl3 r6,r2,r8
72: jeql signs
73: cmpl r8,$MAX_EXP_DIF
74: jlss signs
75: ret # return the bigger number.
76:
77: /*
78: * remember the signs:
79: */
80: signs:
81: clrl r3
82: bbc $31,r0,sign2 # if negative remember it.
83: incl r3
84: sign2:
85: clrl r7
86: bbc $31,r4,frac # if negative remember it.
87: incl r7
88: /*
89: * compute 'pure' fraction:
90: */
91: frac:
92: # clear the non fraction parts.
93: andl2 $(0!(EXPMASK | SIGNBIT)),r0
94: # add the hidden bit.
95: orl2 $(0!CLEARHID),r0
96: # clear the non fraction parts.
97: andl2 $(0!(EXPMASK | SIGNBIT)),r4
98: # add the hidden bit.
99: orl2 $(0!CLEARHID),r4
100:
101: /*
102: * shift the smaller operand:
103: */
104: shrq r8,r4,r4
105: eql_exps:
106: cmpl r3,r7
107: jeql add
108: bbc $0,r3,negr4r5
109: /*
110: * negate the pair r0,r1:
111: */
112: clrl r3
113: mcoml r1,r1
114: clrl r9 # r9 - carry flag.
115: incl r1
116: bcc comr0
117: incl r9 # remember the carry.
118: comr0: mcoml r0,r0
119: bbc $0,r9,add
120: incl r0
121:
122: /*
123: * add the fractions:
124: */
125: add:
126: clrl r10 # to remember the sign of the result.
127: addl2 r5,r1
128: adwc r4,r0
129: jgeq norm # if positive go to normelize.
130: incl r10 # else remember it and negate the result.
131: /*
132: * negate the pair r0,r1:
133: */
134: clrl r3
135: mcoml r1,r1
136: clrl r9 # r9 - carry flag.
137: incl r1
138: bcc comr00
139: incl r9 # remember the carry.
140: comr00: mcoml r0,r0
141: bbc $0,r9,norm
142: incl r0
143: norm: callf $4,fnorm
144:
145: /*
146: * add the sign bit
147: */
148: bbs $0,r10,negative
149: bbs $0,r3,negative
150: ret
151: negative:
152: orl2 $SIGNBIT,r0
153: ret
154:
155:
156: /*
157: * negate the pair r4,r5:
158: */
159: negr4r5:
160: clrl r7
161: mcoml r5,r5
162: clrl r9 # r9 - carry flag.
163: incl r5
164: bcc comr4
165: incl r9 # remember the carry.
166: comr4: mcoml r4,r4
167: bbc $0,r9,add
168: incl r4
169: jmp add
170:
171:
172: is_res1:
173: bbs $31,r0,res_op
174: movl r4,r0 # return the smaller operand.
175: movl r5,r1
176: ret
177:
178: is_res2:
179: bbs $31,r4,res_op
180: ret # we allready have the 'result' in r0,r1.
181:
182: res_op:
183: callf $4,fpresop
184: ret
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