4 // Copyright (c) 2000 - 2003, Intel Corporation
5 // All rights reserved.
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37 // http://www.intel.com/software/products/opensource/libraries/num.htm.
40 //==============================================================
41 // 02/02/00 Initial version
42 // 02/08/01 Corrected behavior for all rounding modes.
43 // 05/20/02 Cleaned up namespace and sf0 syntax
44 // 01/20/03 Improved performance
45 //==============================================================
48 //==============================================================
49 // double rint(double x)
50 //==============================================================
52 // general input registers:
64 // floating-point registers:
71 // predicate registers used:
74 // Overview of operation
75 //==============================================================
76 // double rint(double x)
77 // Return an integer value (represented as a double) that is x
78 // rounded to integer in current rounding mode
79 // Inexact is set if x != rint(x)
80 //==============================================================
83 // if the exponent is > 1003e => 3F(true) = 63(decimal)
84 // we have a significand of 64 bits 1.63-bits.
85 // If we multiply by 2^63, we no longer have a fractional part
86 // So input is an integer value already.
89 // if the exponent is >= 10033 => 34(true) = 52(decimal)
91 // we have a significand of 53 bits 1.52-bits. (implicit 1)
92 // If we multiply by 2^52, we no longer have a fractional part
93 // So input is an integer value already.
96 // if the exponent is > 10016 => 17(true) = 23(decimal)
97 // we have a significand of 24 bits 1.23-bits. (implicit 1)
98 // If we multiply by 2^23, we no longer have a fractional part
99 // So input is an integer value already.
102 GLOBAL_IEEE754_ENTRY(rint)
105 getf.exp rSignexp = f8 // Get signexp, recompute if unorm
106 fclass.m p7,p0 = f8, 0x0b // Test x unorm
107 addl rBigexp = 0x10033, r0 // Set exponent at which is integer
110 mov rM1 = -1 // Set all ones
111 fcvt.fx.s1 fXInt = f8 // Convert to int in significand
112 mov rExpMask = 0x1FFFF // Form exponent mask
117 mov rFpsr = ar40 // Read fpsr -- check rc.s0
118 fclass.m p6,p0 = f8, 0x1e3 // Test x natval, nan, inf
122 setf.sig fTmp = rM1 // Make const for setting inexact
123 fnorm.s1 fNormX = f8 // Normalize input
124 (p7) br.cond.spnt RINT_UNORM // Branch if x unorm
130 // Return here from RINT_UNORM
132 and rExp = rSignexp, rExpMask // Get biased exponent
133 (p6) fma.d.s0 f8 = f8, f1, f0 // Result if x natval, nan, inf
134 (p6) br.ret.spnt b0 // Exit if x natval, nan, inf
139 mov rRcs0Mask = 0x0c00 // Mask for rc.s0
140 fcvt.xf f8 = fXInt // Result assume |x| < 2^52
141 cmp.ge p7,p8 = rExp, rBigexp // Is |x| >= 2^52?
145 // We must correct result if |x| >= 2^52
148 (p7) fma.d.s0 f8 = fNormX, f1, f0 // If |x| >= 2^52, result x
155 fcmp.eq.unc.s1 p0, p9 = f8, fNormX // Is result = x ?
160 (p8) fmerge.s f8 = fNormX, f8 // Make sure sign rint(x) = sign x
166 (p8) and rRcs0 = rFpsr, rRcs0Mask // Get rounding mode for sf0
172 // If |x| < 2^52 we must test for other rounding modes
174 (p8) cmp.ne.unc p10,p0 = rRcs0, r0 // Test for other rounding modes
175 (p9) fmpy.s0 fTmp = fTmp, fTmp // Dummy to set inexact
180 (p10) br.cond.spnt RINT_NOT_ROUND_NEAREST // Branch if not round nearest
181 br.ret.sptk b0 // Exit main path if round nearest
190 getf.exp rSignexp = fNormX // Get signexp, recompute if unorm
191 fcmp.eq.s0 p7,p0 = f8, f0 // Dummy op to set denormal flag
192 br.cond.sptk RINT_COMMON // Return to main path
196 RINT_NOT_ROUND_NEAREST:
197 // Here if not round to nearest, and |x| < 2^52
198 // Set rounding mode of s2 to that of s0, and repeat the conversion using s2
208 fcvt.fx.s2 fXInt = fNormX // Convert to int in significand
215 fcvt.xf f8 = fXInt // Expected result
220 // Be sure sign of result = sign of input. Fixes cases where result is 0.
223 fmerge.s f8 = fNormX, f8
224 br.ret.sptk b0 // Exit main path
228 GLOBAL_IEEE754_END(rint)
229 libm_alias_double_other (__rint, rint)