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7 // Contributed 2000 by the Intel Numerics Group, Intel Corporation
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41 //==============================================================
42 // 10/25/00 Initial version
43 // 06/14/01 Changed cmp to an equivalent form
44 // 05/20/02 Cleaned up namespace and sf0 syntax
45 // 01/20/03 Improved performance and reduced code size
46 // 04/18/03 Eliminate possible WAW dependency warning
47 //==============================================================
50 //==============================================================
51 // long double roundl(long double x)
52 //==============================================================
54 // general input registers:
64 // floating-point registers:
73 // predicate registers used:
76 // Overview of operation
77 //==============================================================
78 // long double roundl(long double x)
79 // Return an integer value (represented as a long double) that is x
80 // rounded to nearest integer, halfway cases rounded away from
82 // if x>0 result = trunc(x+0.5)
83 // if x<0 result = trunc(x-0.5)
85 //==============================================================
88 // if the exponent is > 1003e => 3F(true) = 63(decimal)
89 // we have a significand of 64 bits 1.63-bits.
90 // If we multiply by 2^63, we no longer have a fractional part
91 // So input is an integer value already.
94 // if the exponent is >= 10033 => 34(true) = 52(decimal)
96 // we have a significand of 53 bits 1.52-bits. (implicit 1)
97 // If we multiply by 2^52, we no longer have a fractional part
98 // So input is an integer value already.
101 // if the exponent is > 10016 => 17(true) = 23(decimal)
102 // we have a significand of 24 bits 1.23-bits. (implicit 1)
103 // If we multiply by 2^23, we no longer have a fractional part
104 // So input is an integer value already.
108 GLOBAL_LIBM_ENTRY(roundl)
111 getf.exp rSignexp = f8 // Get signexp, recompute if unorm
112 fcvt.fx.trunc.s1 fXtruncInt = f8 // Convert to int in significand
113 addl rBigexp = 0x1003e, r0 // Set exponent at which is integer
116 mov rExpHalf = 0x0FFFE // Form sign and exponent of 0.5
117 fnorm.s1 fNormX = f8 // Normalize input
118 mov rExpMask = 0x1FFFF // Form exponent mask
123 setf.exp fHalf = rExpHalf // Form 0.5
124 mov rExpMHalf = 0x2FFFE // Form sign and exponent of -0.5
125 fclass.m p7,p0 = f8, 0x0b // Test x unorm
130 setf.exp fMHalf = rExpMHalf // Form -0.5
131 fclass.m p6,p0 = f8, 0x1e3 // Test x natval, nan, inf
132 (p7) br.cond.spnt ROUND_UNORM // Branch if x unorm
137 // Return here from ROUND_UNORM
140 fcmp.lt.s1 p8,p9 = f8, f0 // Test if x < 0
144 and rExp = rSignexp, rExpMask // Get biased exponent
145 (p6) fma.s0 f8 = f8, f1, f0 // Result if x natval, nan, inf
146 (p6) br.ret.spnt b0 // Exit if x natval, nan, inf
151 cmp.lt p6,p0 = rExp, rExpHalf // Is |x| < 0.5?
152 fcvt.xf f8 = fXtruncInt // Pre-Result if 0.5 <= |x| < 2^63
153 cmp.ge p7,p0 = rExp, rBigexp // Is |x| >= 2^63?
156 cmp.lt p10,p0 = rExp, rExpHalf // Is |x| < 0.5?
162 // We must correct result if |x| < 0.5, or |x| >= 2^63
163 .pred.rel "mutex",p6,p7
166 (p6) fmerge.s f8 = fNormX, f0 // If |x| < 0.5, result sgn(x)*0
170 (p7) cmp.eq p10,p0 = r0, r0 // Also turn on p10 if |x| >= 2^63
171 (p7) fma.s0 f8 = fNormX, f1, f0 // If |x| >= 2^63, result x
172 (p10) br.ret.spnt b0 // Exit |x| < 0.5 or |x| >= 2^63
176 // Here if 0.5 <= |x| < 2^63
179 fms.s1 fRem = fNormX, f1, f8 // Get remainder = x - trunc(x)
186 (p8) fcmp.le.s1 p8,p0 = fRem, fMHalf
191 (p9) fcmp.ge.s1 p9,p0 = fRem, fHalf
196 // If x < 0 and remainder <= -0.5, then subtract 1 from result
197 // If x > 0 and remainder >= +0.5, then add 1 to result
198 .pred.rel "mutex",p8,p9
201 (p8) fms.s0 f8 = f8, f1, f1
206 (p9) fma.s0 f8 = f8, f1, f1
215 getf.exp rSignexp = fNormX // Get signexp, recompute if unorm
216 fcmp.eq.s0 p7,p0 = f8, f0 // Dummy op to set denormal flag
217 br.cond.sptk ROUND_COMMON // Return to main path
221 GLOBAL_LIBM_END(roundl)