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5733b822 SL |
1 | #ifdef LIBC_SCCS |
2 | .asciz "@(#)addf.s 1.1 (Berkeley/CCI) %G%" | |
3 | #endif LIBC_SCCS | |
4 | ||
5 | #include <tahoemath//fp.h> | |
6 | #include "DEFS.h" | |
7 | ||
8 | XENTRY(addf, R2|R3|R4|R5|R6|R7|R8|R9|R10) | |
9 | /* | |
10 | * see which operand has a greater exponent | |
11 | * The greater one will be fetched into r0,r2,r3. | |
12 | * r0- 'pure' fraction, r2 - exponent, r3 - sign). | |
13 | * The smaller operand will be fetched into r4,r6,r7. | |
14 | */ | |
15 | clrl r1 | |
16 | andl3 $EXPMASK,4(fp),r0 | |
17 | andl3 $EXPMASK,12(fp),r1 | |
18 | cmpl r0,r1 | |
19 | jgtr first_greater | |
20 | ||
21 | movl 12(fp),r0 # bigger operand to r0 | |
22 | ||
23 | movl 4(fp),r4 # smaller operand to r4 | |
24 | jmp expo | |
25 | ||
26 | first_greater: | |
27 | movl 4(fp),r0 # bigger operand to r0 | |
28 | ||
29 | movl 12(fp),r4 # smaller operand to r4 | |
30 | ||
31 | ||
32 | /* | |
33 | *compute exponents: | |
34 | */ | |
35 | expo: | |
36 | andl3 $EXPMASK,r0,r2 # r2 will hold the exponent of greater operand. | |
37 | jeql is_res1 # check for reserved operand. | |
38 | shrl $EXPSHIFT,r2,r2 | |
39 | ||
40 | ||
41 | andl3 $EXPMASK,r4,r6 # r6 will hold the exponent of smaller operand. | |
42 | jeql is_res2 # check for reserved operand. | |
43 | shrl $EXPSHIFT,r6,r6 | |
44 | /* | |
45 | *compare the exponents: | |
46 | */ | |
47 | subl3 r6,r2,r8 | |
48 | jeql signs | |
49 | cmpl r8,$MAX_EXP_DIF | |
50 | jlss signs | |
51 | ret # return the bigger number. | |
52 | ||
53 | /* | |
54 | *remember the signs: | |
55 | */ | |
56 | signs: | |
57 | clrl r3 | |
58 | bbc $31,r0,sign2 # if negative remember it.(R3=1) | |
59 | incl r3 | |
60 | sign2: | |
61 | clrl r7 | |
62 | bbc $31,r4,frac # if negative remember it.(R7=1) | |
63 | incl r7 | |
64 | /* | |
65 | *compute 'pure' fraction: | |
66 | */ | |
67 | frac: | |
68 | # clear the non fraction parts. | |
69 | andl2 $(0!(EXPMASK | SIGNBIT)),r0 | |
70 | # add the hidden bit. | |
71 | orl2 $(0!CLEARHID),r0 | |
72 | # clear the non fraction parts. | |
73 | andl2 $(0!(EXPMASK | SIGNBIT)),r4 | |
74 | # add the hidden bit. | |
75 | orl2 $(0!CLEARHID),r4 | |
76 | ||
77 | /* | |
78 | *shift the smaller operand: | |
79 | */ | |
80 | shar r8,r4,r4 | |
81 | eql_exps: | |
82 | cmpl r3,r7 | |
83 | jeql add | |
84 | bbc $0,r3,negr4 | |
85 | /* | |
86 | *negate r0: | |
87 | */ | |
88 | clrl r3 | |
89 | mnegl r0,r0 | |
90 | ||
91 | /* | |
92 | *add the fractions: | |
93 | */ | |
94 | add: | |
95 | clrl r10 | |
96 | addl2 r4,r0 | |
97 | jgeq norm | |
98 | incl r10 | |
99 | /* | |
100 | *negate the pair r0,r1: | |
101 | */ | |
102 | mnegl r0,r0 | |
103 | norm: callf $4,sfnorm | |
104 | ||
105 | /* | |
106 | *add the sign bit | |
107 | */ | |
108 | bbs $0,r10,negative | |
109 | bbs $0,r3,negative # the bigger operand was negative. | |
110 | ret | |
111 | negative: | |
112 | orl2 $SIGNBIT,r0 | |
113 | ret | |
114 | ||
115 | ||
116 | /* | |
117 | *negate r4: | |
118 | */ | |
119 | negr4: | |
120 | mnegl r4,r4 | |
121 | jmp add | |
122 | ||
123 | ||
124 | is_res1: | |
125 | bbs $31,r0,res_op | |
126 | movl r4,r0 # return the smaller operand. | |
127 | ret | |
128 | ||
129 | is_res2: | |
130 | bbs $31,r4,res_op | |
131 | ret # we allready have the 'result' in r0,r1. | |
132 | ||
133 | res_op: | |
134 | callf $4,sfpresop | |
135 | ret |