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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 "@(#)addf.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(addf, 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,r2,r3.
34: * r0- 'pure' fraction, r2 - exponent, r3 - sign).
35: * The smaller operand will be fetched into r4,r6,r7.
36: */
37: clrl r1
38: andl3 $EXPMASK,4(fp),r0
39: andl3 $EXPMASK,12(fp),r1
40: cmpl r0,r1
41: jgtr first_greater
42:
43: movl 12(fp),r0 # bigger operand to r0
44:
45: movl 4(fp),r4 # smaller operand to r4
46: jmp expo
47:
48: first_greater:
49: movl 4(fp),r0 # bigger operand to r0
50:
51: movl 12(fp),r4 # smaller operand to r4
52:
53:
54: /*
55: *compute exponents:
56: */
57: expo:
58: andl3 $EXPMASK,r0,r2 # r2 will hold the exponent of greater operand.
59: jeql is_res1 # check for reserved operand.
60: shrl $EXPSHIFT,r2,r2
61:
62:
63: andl3 $EXPMASK,r4,r6 # r6 will hold the exponent of smaller operand.
64: jeql is_res2 # check for reserved operand.
65: shrl $EXPSHIFT,r6,r6
66: /*
67: *compare the exponents:
68: */
69: subl3 r6,r2,r8
70: jeql signs
71: cmpl r8,$MAX_EXP_DIF
72: jlss signs
73: ret # return the bigger number.
74:
75: /*
76: *remember the signs:
77: */
78: signs:
79: clrl r3
80: bbc $31,r0,sign2 # if negative remember it.(R3=1)
81: incl r3
82: sign2:
83: clrl r7
84: bbc $31,r4,frac # if negative remember it.(R7=1)
85: incl r7
86: /*
87: *compute 'pure' fraction:
88: */
89: frac:
90: # clear the non fraction parts.
91: andl2 $(0!(EXPMASK | SIGNBIT)),r0
92: # add the hidden bit.
93: orl2 $(0!CLEARHID),r0
94: # clear the non fraction parts.
95: andl2 $(0!(EXPMASK | SIGNBIT)),r4
96: # add the hidden bit.
97: orl2 $(0!CLEARHID),r4
98:
99: /*
100: *shift the smaller operand:
101: */
102: shar r8,r4,r4
103: eql_exps:
104: cmpl r3,r7
105: jeql add
106: bbc $0,r3,negr4
107: /*
108: *negate r0:
109: */
110: clrl r3
111: mnegl r0,r0
112:
113: /*
114: *add the fractions:
115: */
116: add:
117: clrl r10
118: addl2 r4,r0
119: jgeq norm
120: incl r10
121: /*
122: *negate the pair r0,r1:
123: */
124: mnegl r0,r0
125: norm: callf $4,sfnorm
126:
127: /*
128: *add the sign bit
129: */
130: bbs $0,r10,negative
131: bbs $0,r3,negative # the bigger operand was negative.
132: ret
133: negative:
134: orl2 $SIGNBIT,r0
135: ret
136:
137:
138: /*
139: *negate r4:
140: */
141: negr4:
142: mnegl r4,r4
143: jmp add
144:
145:
146: is_res1:
147: bbs $31,r0,res_op
148: movl r4,r0 # return the smaller operand.
149: ret
150:
151: is_res2:
152: bbs $31,r4,res_op
153: ret # we allready have the 'result' in r0,r1.
154:
155: res_op:
156: callf $4,sfpresop
157: ret
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