about summary refs log tree commit diff
path: root/sysdeps/ia64/fpu/s_logbl.S
blob: 0100a3e9d7cab5fa097b178e767d45bae317186b (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
.file "logbl.s"


// Copyright (c) 2000 - 2003, Intel Corporation
// All rights reserved.
//
// Contributed 2000 by the Intel Numerics Group, Intel Corporation
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//
// * Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
//
// * The name of Intel Corporation may not be used to endorse or promote
// products derived from this software without specific prior written
// permission.

// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL INTEL OR ITS
// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
// OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY OR TORT (INCLUDING
// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// Intel Corporation is the author of this code, and requests that all
// problem reports or change requests be submitted to it directly at
// http://www.intel.com/software/products/opensource/libraries/num.htm.
//
// History
//==============================================================
// 02/02/00 Initial version
// 02/16/00 Modified to conform to C9X
// 03/16/00 Improved speed
// 04/04/00 Unwind support added
// 05/30/00 Fixed bug when x double-extended denormal
// 08/15/00 Bundle added after call to __libm_error_support to properly
//          set [the previously overwritten] GR_Parameter_RESULT.
// 05/20/02 Cleaned up namespace and sf0 syntax
// 01/20/03 Improved performance
//
// API
//==============================================================
// long double logbl( long double x );
//
// Overview of operation
//==============================================================
// The logbl function extracts the exponent of x as an integer in
// floating-point format.
// logbl computes log2 of x as a long double
//
// logbl is similar to ilogbl but differs in the following ways:
//         +-inf
//            ilogbl: returns INT_MAX
//             logbl: returns +inf
//         Nan  returns FP_LOGBNAN (which is either INT_MAX or INT_MIN)
//            ilogbl: returns INT_MAX (7fffffff)
//             logbl: returns QNAN (quietized SNAN)
//         0    returns FP_ILOGB0 (which is either INT_MIN or -INT_MAX)
//            ilogbl: returns -INT_MAX (80000001)
//             logbl: returns -inf, raises the divide-by-zero exception,
//                   and calls libm_error_support to set domain error
//
// Registers used
//==============================================================
// general registers used:
// r26 -> r38
// r35 -> r38 used as parameters to error path
//
// predicate registers used:
// p6, p7, p8
// floating-point registers used:
// f9, f10, f11
// f8, input

rExpBias            = r26
rExpMask            = r27
rSignexp_x          = r28
rExp_x              = r29
rTrueExp_x          = r30
rExp_2to64          = r31

GR_SAVE_PFS         = r32
GR_SAVE_B0          = r33
GR_SAVE_GP          = r34

GR_Parameter_X      = r35
GR_Parameter_Y      = r36
GR_Parameter_RESULT = r37
GR_Parameter_TAG    = r38

fExp_in_signif      = f9
fNorm_x             = f10
fFloat_Exp          = f10
f2to64              = f11

.section .text
GLOBAL_LIBM_ENTRY(logbl)

// X NORMAL
// TrueExp_x = exp(f8) - 0xffff
// sig = TrueExp_x
// f8 = convert_to_fp (sig))
{ .mfi
      getf.exp        rSignexp_x = f8
      fclass.m        p8,p0 = f8, 0x0b   // Test for x unorm
      mov             rExpBias = 0xffff  // Exponent bias
}
{ .mfi
      nop.m           0
      fnorm.s1        fNorm_x = f8
      mov             rExpMask = 0x1ffff // Exponent mask
}
;;

// Form signexp of 2^64 in case need to scale denormal
{ .mfb
      mov             rExp_2to64 = 0x1003f
      fclass.m        p6,p0 = f8, 0x1e3  // Test x natval, nan, inf
(p8)  br.cond.spnt    LOGB_DENORM        // Branch if x unorm
}
;;

LOGB_COMMON:
// Return here from LOGB_DENORM
{ .mfi
      and             rExp_x = rSignexp_x, rExpMask // Get biased exponent
      fclass.m        p7,p0 = f8, 0x07   // Test x zero
      nop.i           0
}
;;

// X NAN or INFINITY, return f8 * f8
{ .mfb
      sub             rTrueExp_x = rExp_x, rExpBias // Get true exponent
(p6)  fma.s0          f8= f8,f8,f0       // Result if x natval, nan, inf
(p6)  br.ret.spnt     b0                 // Exit if x natval, nan, inf
}
;;

{ .mib
      setf.sig        fExp_in_signif = rTrueExp_x // Exponent as integer in fp
      nop.i 999
(p7)  br.cond.spnt    LOGB_ZERO
}
;;

// Result can be represented in less than 24 bits, so no precision completer
// is needed.
{ .mfb
      nop.m           0
      fcvt.xf         f8 = fExp_in_signif
      br.ret.sptk     b0                 // Exit main path, 0 < |x| < inf
}
;;

LOGB_DENORM:
// Form 2^64 in case need to scale denormal
// Check to see if double-extended denormal
{ .mfi
      setf.exp        f2to64 = rExp_2to64
      fclass.m        p8,p0 = fNorm_x, 0x0b
      nop.i           0
}
;;

{ .mfi
      nop.m           0
      fcmp.eq.s0      p7,p0 = f8, f0           // Dummy op to set denormal flag
      nop.i           0
}
;;

// If double-extended denormal add 64 to exponent bias for scaling
// If double-extended denormal form x * 2^64 which is normal
{ .mfi
(p8)  add             rExpBias = 64, rExpBias
(p8)  fmpy.s1         fNorm_x = fNorm_x, f2to64
      nop.i           0
}
;;

// Logic is the same as normal path but use normalized input
{ .mib
      getf.exp        rSignexp_x = fNorm_x
      nop.i           0
      br.cond.sptk    LOGB_COMMON              // Return to main path
}
;;

LOGB_ZERO:
// Here if x zero
// f10  = -|f8|
// f9  = 1.0/f10 = -1.0/|f8| = -inf

{ .mmf
      alloc           r32=ar.pfs,1,2,4,0
      mov             GR_Parameter_TAG = 150  // Error code
      fmerge.ns       f10 = f0,f8
}
;;

{ .mfb
      nop.m           0
      frcpa.s0        f9,p6 = f1,f10          // Produce -inf, Z flag
      br.cond.sptk    __libm_error_region     // Call error support
}
;;

GLOBAL_LIBM_END(logbl)
libm_alias_ldouble_other (logb, logb)


LOCAL_LIBM_ENTRY(__libm_error_region)
.prologue

{ .mfi
        add   GR_Parameter_Y=-32,sp           // Parameter 2 value
        nop.f 0
.save   ar.pfs,GR_SAVE_PFS
        mov  GR_SAVE_PFS=ar.pfs               // Save ar.pfs
}
{ .mfi
.fframe 64
        add sp=-64,sp                         // Create new stack
        nop.f 0
        mov GR_SAVE_GP=gp                     // Save gp
};;

{ .mmi
        stfe [GR_Parameter_Y] = f0,16         // STORE Parameter 2 on stack
        add GR_Parameter_X    = 16,sp         // Parameter 1 address
.save   b0, GR_SAVE_B0
        mov GR_SAVE_B0=b0                     // Save b0
};;

.body
{ .mib
        stfe [GR_Parameter_X] = f8            // STORE Parameter 1 on stack
        add   GR_Parameter_RESULT = 0,GR_Parameter_Y    // Parameter 3 address
        nop.b 0
}
{ .mib
        stfe [GR_Parameter_Y] = f9            // Store Parameter 3 on stack
        add   GR_Parameter_Y = -16,GR_Parameter_Y
        br.call.sptk b0=__libm_error_support# // Call error handling function
};;

{ .mmi
        add   GR_Parameter_RESULT = 48,sp
        nop.m 0
        nop.i 0
};;

{ .mmi
        ldfe  f8 = [GR_Parameter_RESULT]       // Get return result off stack
.restore sp
        add   sp = 64,sp                       // Restore stack pointer
        mov   b0 = GR_SAVE_B0                  // Restore return address
};;

{ .mib
        mov   gp = GR_SAVE_GP                  // Restore gp
        mov   ar.pfs = GR_SAVE_PFS             // Restore ar.pfs
        br.ret.sptk   b0
};;

LOCAL_LIBM_END(__libm_error_region)


.type   __libm_error_support#,@function
.global __libm_error_support#