1.file "truncl.s"
2
3
4// Copyright (c) 2000 - 2003, Intel Corporation
5// All rights reserved.
6//
7//
8// Redistribution and use in source and binary forms, with or without
9// modification, are permitted provided that the following conditions are
10// met:
11//
12// * Redistributions of source code must retain the above copyright
13// notice, this list of conditions and the following disclaimer.
14//
15// * Redistributions in binary form must reproduce the above copyright
16// notice, this list of conditions and the following disclaimer in the
17// documentation and/or other materials provided with the distribution.
18//
19// * The name of Intel Corporation may not be used to endorse or promote
20// products derived from this software without specific prior written
21// permission.
22
23// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
24// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
25// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
26// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL INTEL OR ITS
27// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
28// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
29// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
30// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
31// OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY OR TORT (INCLUDING
32// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
33// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
34//
35// Intel Corporation is the author of this code, and requests that all
36// problem reports or change requests be submitted to it directly at
37// http://www.intel.com/software/products/opensource/libraries/num.htm.
38//
39// History
40//==============================================================
41// 07/07/00 Created
42// 05/20/02 Cleaned up namespace and sf0 syntax
43// 01/20/03 Improved performance and reduced code size
44//==============================================================
45
46// API
47//==============================================================
48// long double truncl(long double x)
49//==============================================================
50
51// general input registers:
52// r14 - r18
53
54rExpBias   = r14
55rSignexp   = r15
56rExp       = r16
57rExpMask   = r17
58rBigexp    = r18
59
60// floating-point registers:
61// f8 - f10
62
63fXtruncInt = f9
64fNormX     = f10
65
66// predicate registers used:
67// p6, p7
68
69// Overview of operation
70//==============================================================
71// long double truncl(long double x)
72// Return an integer value (represented as a long double) less than or
73// equal to x in magnitude.
74// This is x rounded toward zero to an integral value.
75//==============================================================
76
77// double_extended
78// if the exponent is > 1003e => 3F(true) = 63(decimal)
79// we have a significand of 64 bits 1.63-bits.
80// If we multiply by 2^63, we no longer have a fractional part
81// So input is an integer value already.
82
83// double
84// if the exponent is >= 10033 => 34(true) = 52(decimal)
85// 34 + 3ff = 433
86// we have a significand of 53 bits 1.52-bits. (implicit 1)
87// If we multiply by 2^52, we no longer have a fractional part
88// So input is an integer value already.
89
90// single
91// if the exponent is > 10016 => 17(true) = 23(decimal)
92// we have a significand of 24 bits 1.23-bits. (implicit 1)
93// If we multiply by 2^23, we no longer have a fractional part
94// So input is an integer value already.
95
96.section .text
97GLOBAL_LIBM_ENTRY(truncl)
98
99{ .mfi
100      getf.exp         rSignexp  = f8        // Get signexp, recompute if unorm
101      fcvt.fx.trunc.s1 fXtruncInt  = f8      // Convert to int in significand
102      addl             rBigexp = 0x1003e, r0 // Set exponent at which is integer
103}
104{ .mfi
105      mov              rExpBias    = 0x0FFFF // Form exponent bias
106      fnorm.s1         fNormX  = f8          // Normalize input
107      mov              rExpMask    = 0x1FFFF // Form exponent mask
108}
109;;
110
111{ .mfi
112      nop.m            0
113      fclass.m         p7,p0 = f8, 0x0b      // Test x unorm
114      nop.i            0
115}
116;;
117
118{ .mfb
119      nop.m            0
120      fclass.m         p6,p0 = f8, 0x1e3     // Test x natval, nan, inf
121(p7)  br.cond.spnt     TRUNC_UNORM           // Branch if x unorm
122}
123;;
124
125TRUNC_COMMON:
126// Return here from TRUNC_UNORM
127{ .mfb
128      and              rExp = rSignexp, rExpMask // Get biased exponent
129(p6)  fma.s0           f8 = f8, f1, f0       // Result if x natval, nan, inf
130(p6)  br.ret.spnt      b0                    // Exit if x natval, nan, inf
131}
132;;
133
134{ .mfi
135      cmp.lt           p6,p0 = rExp, rExpBias // Is |x| < 1?
136      fcvt.xf          f8 = fXtruncInt        // Result, assume 1 <= |x| < 2^63
137      cmp.ge           p7,p0 = rExp, rBigexp  // Is |x| >= 2^63?
138}
139;;
140
141// We must correct result if |x| < 1, or |x| >= 2^63
142.pred.rel "mutex",p6,p7
143{ .mfi
144      nop.m            0
145(p6)  fmerge.s         f8 = fNormX, f0        // If |x| < 1, result sgn(x)*0
146      nop.i            0
147}
148{ .mfb
149      nop.m            0
150(p7)  fma.s0           f8 = fNormX, f1, f0    // If |x| >= 2^63, result x
151      br.ret.sptk      b0                     // Exit main path
152}
153;;
154
155
156TRUNC_UNORM:
157// Here if x unorm
158{ .mfb
159      getf.exp         rSignexp  = fNormX     // Get signexp, recompute if unorm
160      fcmp.eq.s0       p7,p0 = f8, f0         // Dummy op to set denormal flag
161      br.cond.sptk     TRUNC_COMMON           // Return to main path
162}
163;;
164
165GLOBAL_LIBM_END(truncl)
166libm_alias_ldouble_other (trunc, trunc)
167