1.file "significand.s"
2
3
4// Copyright (c) 2000 - 2003, Intel Corporation
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22
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38//
39// History
40//==============================================================
41// 02/02/00 Initial version
42// 04/04/00 Unwind support added
43// 05/31/00 Fixed bug when x a double-extended denormal
44// 05/20/02 Cleaned up namespace and sf0 syntax
45// 02/10/03 Reordered header: .section, .global, .proc, .align
46//
47// API
48//==============================================================
49// double significand(double x)
50//
51// Overview of operation
52//==============================================================
53// If x = sig * 2**n with 1 <= sig < 2
54// significand returns sig
55//
56// predicate registers used:
57// p6, p7
58//
59// floating-point registers used:
60// f8, f9, f10
61
62.section .text
63GLOBAL_LIBM_ENTRY(significand)
64
65// qnan snan inf norm     unorm 0 -+
66// 1    1    1   0        0     1 11
67
68// f10 gets f8(sign) with f1(exp,significand)
69{ .mfi
70      nop.m 999
71      fmerge.s       f10 = f8,f1
72      nop.i 999
73}
74{ .mfi
75      nop.m 999
76      fnorm.s0          f9  = f8
77      nop.i 999 ;;
78}
79
80// Test for denormal input
81{ .mfi
82      nop.m 999
83      fclass.m.unc   p7,p0 = f8, 0x0b
84      nop.i 999 ;;
85}
86
87// p6 = TRUE ==> x is not (nan,inf,0)
88//               return sign(f8) exp(f1) significand(f8)
89// else          x is (nan,inf,0)
90//               return sign(f8) exp(f8) significand(f8), normalized.
91{ .mfi
92      nop.m 999
93      fclass.m.unc   p0,p6 = f8, 0xe7
94      nop.i 999 ;;
95}
96
97{ .mmb
98      nop.m 999
99      nop.m 999
100(p7)  br.cond.spnt SIGNIFICAND_DENORM ;; // Branch if x denormal
101}
102
103{ .mfi
104      nop.m 999
105(p6)  fmerge.se      f8 = f10,f8
106      nop.i 999 ;;
107}
108
109{ .mfb
110      nop.m 999
111      fnorm.d.s0        f8 = f8
112      br.ret.sptk    b0 ;;
113}
114
115SIGNIFICAND_DENORM:
116// Here if x denorm
117{ .mfi
118      nop.m 999
119      fmerge.se      f8 = f10,f9
120      nop.i 999 ;;
121}
122
123// Check if fnorm(x) still denormal, means x double-extended denormal
124{ .mfi
125      nop.m 999
126      fclass.m.unc   p7,p0 = f9, 0x0b
127      nop.i 999 ;;
128}
129
130// This will be the final result unless x double-extended denormal
131{ .mfi
132      nop.m 999
133      fnorm.d.s0        f8 = f8
134      nop.i 999 ;;
135}
136
137// If x double-extended denorm, then significand ok, but must merge in
138//    correct signexp
139{ .mfi
140      nop.m 999
141(p7)  fmerge.se      f8 = f10,f8
142      nop.i 999 ;;
143}
144
145// Final normalization if x double-extended denorm
146{ .mfb
147      nop.m 999
148(p7)  fnorm.d.s0        f8 = f8
149      br.ret.sptk    b0 ;;
150}
151
152GLOBAL_LIBM_END(significand)
153