1.file "floor.s"
2
3
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38//
39// History
40//==============================================================
41// 02/02/00 Initial version
42// 03/22/00 Updated to improve performance
43// 06/13/00 Improved speed, fixed setting of inexact flag
44// 06/27/00 Eliminated incorrect invalid flag setting
45// 02/07/01 Corrected sign of zero result in round to -inf mode
46// 05/20/02 Cleaned up namespace and sf0 syntax
47// 01/28/03 Improved performance
48//==============================================================
49
50// API
51//==============================================================
52// double floor(double x)
53//==============================================================
54
55// general input registers:
56// r14 - r18
57
58rSignexp   = r14
59rExp       = r15
60rExpMask   = r16
61rBigexp    = r17
62rM1        = r18
63
64// floating-point registers:
65// f8 - f13
66
67fXInt      = f9
68fNormX     = f10
69fTmp       = f11
70fAdj       = f12
71fPreResult = f13
72
73// predicate registers used:
74// p6 - p9
75
76// Overview of operation
77//==============================================================
78// double floor(double x)
79// Return an integer value (represented as a double) that is the largest
80// value not greater than x
81// This is x rounded toward -infinity to an integral value.
82// Inexact is set if x != floor(x)
83//==============================================================
84
85// double_extended
86// if the exponent is > 1003e => 3F(true) = 63(decimal)
87// we have a significand of 64 bits 1.63-bits.
88// If we multiply by 2^63, we no longer have a fractional part
89// So input is an integer value already.
90
91// double
92// if the exponent is >= 10033 => 34(true) = 52(decimal)
93// 34 + 3ff = 433
94// we have a significand of 53 bits 1.52-bits. (implicit 1)
95// If we multiply by 2^52, we no longer have a fractional part
96// So input is an integer value already.
97
98// single
99// if the exponent is > 10016 => 17(true) = 23(decimal)
100// we have a significand of 24 bits 1.23-bits. (implicit 1)
101// If we multiply by 2^23, we no longer have a fractional part
102// So input is an integer value already.
103
104
105.section .text
106GLOBAL_IEEE754_ENTRY(floor)
107
108{ .mfi
109      getf.exp         rSignexp  = f8        // Get signexp, recompute if unorm
110      fclass.m         p7,p0 = f8, 0x0b      // Test x unorm
111      addl             rBigexp = 0x10033, r0 // Set exponent at which is integer
112}
113{ .mfi
114      mov              rM1 = -1              // Set all ones
115      fcvt.fx.trunc.s1 fXInt  = f8           // Convert to int in significand
116      mov              rExpMask    = 0x1FFFF // Form exponent mask
117}
118;;
119
120{ .mfi
121      nop.m            0
122      fcmp.lt.s1       p8,p9 = f8, f0        // Test x < 0
123      nop.i            0
124}
125{ .mfb
126      setf.sig         fTmp = rM1            // Make const for setting inexact
127      fnorm.s1         fNormX  = f8          // Normalize input
128(p7)  br.cond.spnt     FLOOR_UNORM           // Branch if x unorm
129}
130;;
131
132FLOOR_COMMON:
133// Return here from FLOOR_UNORM
134{ .mfi
135      nop.m            0
136      fclass.m         p6,p0 = f8, 0x1e7     // Test x natval, nan, inf, 0
137      nop.i            0
138}
139;;
140
141.pred.rel "mutex",p8,p9
142{ .mfi
143      nop.m            0
144(p8)  fnma.s1          fAdj = f1, f1, f0     // If x < 0, adjustment is -1
145      nop.i            0
146}
147{ .mfi
148      nop.m            0
149(p9)  fma.s1           fAdj = f0, f0, f0     // If x > 0, adjustment is 0
150      nop.i            0
151}
152;;
153
154{ .mfi
155      nop.m            0
156      fcvt.xf          fPreResult = fXInt    // trunc(x)
157      nop.i            0
158}
159{ .mfb
160      nop.m            0
161(p6)  fma.d.s0         f8 = f8, f1, f0       // Result if x natval, nan, inf, 0
162(p6)  br.ret.spnt      b0                    // Exit if x natval, nan, inf, 0
163}
164;;
165
166{ .mmi
167      and              rExp = rSignexp, rExpMask // Get biased exponent
168;;
169      cmp.ge           p7,p6 = rExp, rBigexp  // Is |x| >= 2^52?
170      nop.i            0
171}
172;;
173
174{ .mfi
175      nop.m            0
176(p6)  fma.d.s0         f8 = fPreResult, f1, fAdj // Result if !int, |x| < 2^52
177      nop.i            0
178}
179{ .mfi
180      nop.m            0
181(p7)  fma.d.s0         f8 = fNormX, f1, f0    // Result, if |x| >= 2^52
182      nop.i            0
183}
184;;
185
186{ .mfi
187      nop.m            0
188(p6)  fcmp.eq.unc.s1   p8, p9 = fPreResult, fNormX // Is trunc(x) = x ?
189      nop.i            0
190}
191;;
192
193{ .mfi
194      nop.m            0
195(p9)  fmpy.s0          fTmp = fTmp, fTmp      // Dummy to set inexact
196      nop.i            0
197}
198{ .mfb
199      nop.m            0
200(p8)  fma.d.s0         f8 = fNormX, f1, f0    // If x int, result normalized x
201      br.ret.sptk      b0                     // Exit main path, 0 < |x| < 2^52
202}
203;;
204
205
206FLOOR_UNORM:
207// Here if x unorm
208{ .mfb
209      getf.exp         rSignexp  = fNormX     // Get signexp, recompute if unorm
210      fcmp.eq.s0       p7,p0 = f8, f0         // Dummy op to set denormal flag
211      br.cond.sptk     FLOOR_COMMON           // Return to main path
212}
213;;
214
215GLOBAL_IEEE754_END(floor)
216libm_alias_double_other (__floor, floor)
217