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1.1 root 1: #ifdef LIBC_SCCS
2: .asciz "@(#)addd.s 1.1 (Berkeley/CCI) 7/2/86"
3: #endif LIBC_SCCS
4:
5: #include <tahoemath/fp.h>
6: #include "DEFS.h"
7:
8: XENTRY(addd, 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,r1,r2,r3.
12: * r0,r1 - 'pure' fraction, r2 - exponent, r3 - sign).
13: * The smaller operand will be fetched into r4,r5,r6,r7.
14: */
15: andl3 $EXPMASK,4(fp),r0
16: andl3 $EXPMASK,12(fp),r1
17: cmpl r0,r1
18: jgtr first_greater
19:
20: movl 12(fp),r0 # bigger operand to r0,r1
21: movl 16(fp),r1
22:
23: movl 4(fp),r4 # smaller operand to r4,r5
24: movl 8(fp),r5
25: jmp expo
26:
27: first_greater:
28: movl 4(fp),r0 # bigger operand to r0,r1
29: movl 8(fp),r1
30:
31: movl 12(fp),r4 # smaller operand to r4,r5
32: movl 16(fp),r5
33:
34: /*
35: * compute exponents:
36: */
37: expo:
38: andl3 $EXPMASK,r0,r2 # r2 will hold the exponent.
39: jeql is_res1 # check for reserved operand.
40: shrl $EXPSHIFT,r2,r2
41:
42:
43: andl3 $EXPMASK,r4,r6 # r6 will hold the exponent.
44: jeql is_res2 # check for reserved operand.
45: shrl $EXPSHIFT,r6,r6
46: /*
47: * compare the exponents:
48: */
49: subl3 r6,r2,r8
50: jeql signs
51: cmpl r8,$MAX_EXP_DIF
52: jlss signs
53: ret # return the bigger number.
54:
55: /*
56: * remember the signs:
57: */
58: signs:
59: clrl r3
60: bbc $31,r0,sign2 # if negative remember it.
61: incl r3
62: sign2:
63: clrl r7
64: bbc $31,r4,frac # if negative remember it.
65: incl r7
66: /*
67: * compute 'pure' fraction:
68: */
69: frac:
70: # clear the non fraction parts.
71: andl2 $(0!(EXPMASK | SIGNBIT)),r0
72: # add the hidden bit.
73: orl2 $(0!CLEARHID),r0
74: # clear the non fraction parts.
75: andl2 $(0!(EXPMASK | SIGNBIT)),r4
76: # add the hidden bit.
77: orl2 $(0!CLEARHID),r4
78:
79: /*
80: * shift the smaller operand:
81: */
82: shrq r8,r4,r4
83: eql_exps:
84: cmpl r3,r7
85: jeql add
86: bbc $0,r3,negr4r5
87: /*
88: * negate the pair r0,r1:
89: */
90: clrl r3
91: mcoml r1,r1
92: clrl r9 # r9 - carry flag.
93: incl r1
94: bcc comr0
95: incl r9 # remember the carry.
96: comr0: mcoml r0,r0
97: bbc $0,r9,add
98: incl r0
99:
100: /*
101: * add the fractions:
102: */
103: add:
104: clrl r10 # to remember the sign of the result.
105: addl2 r5,r1
106: adwc r4,r0
107: jgeq norm # if positive go to normelize.
108: incl r10 # else remember it and negate the result.
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 comr00
117: incl r9 # remember the carry.
118: comr00: mcoml r0,r0
119: bbc $0,r9,norm
120: incl r0
121: norm: callf $4,fnorm
122:
123: /*
124: * add the sign bit
125: */
126: bbs $0,r10,negative
127: bbs $0,r3,negative
128: ret
129: negative:
130: orl2 $SIGNBIT,r0
131: ret
132:
133:
134: /*
135: * negate the pair r4,r5:
136: */
137: negr4r5:
138: clrl r7
139: mcoml r5,r5
140: clrl r9 # r9 - carry flag.
141: incl r5
142: bcc comr4
143: incl r9 # remember the carry.
144: comr4: mcoml r4,r4
145: bbc $0,r9,add
146: incl r4
147: jmp add
148:
149:
150: is_res1:
151: bbs $31,r0,res_op
152: movl r4,r0 # return the smaller operand.
153: movl r5,r1
154: ret
155:
156: is_res2:
157: bbs $31,r4,res_op
158: ret # we allready have the 'result' in r0,r1.
159:
160: res_op:
161: callf $4,fpresop
162: ret
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