.file "roundl.s"

// Copyright (c) 2000 - 2003, Intel Corporation

// All rights reserved.

//

// Contributed 2000 by the Intel Numerics Group, Intel Corporation

//

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//

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// problem reports or change requests be submitted to it directly at

// http://www.intel.com/software/products/opensource/libraries/num.htm.

//

// History

//==============================================================

// 10/25/00 Initial version

// 06/14/01 Changed cmp to an equivalent form

// 05/20/02 Cleaned up namespace and sf0 syntax

// 01/20/03 Improved performance and reduced code size

// 04/18/03 Eliminate possible WAW dependency warning

// 09/03/03 Improved performance

//==============================================================

// API

//==============================================================

// long double roundl(long double x)

//==============================================================

// general input registers:

// r14 - r18

rSignexp   = r14

rExp       = r15

rExpMask   = r16

rBigexp    = r17

rExpHalf   = r18

// floating-point registers:

// f8 - f13

fXtruncInt = f9

fNormX     = f10

fHalf      = f11

fInc       = f12

fRem       = f13

// predicate registers used:

// p6 - p10

// Overview of operation

//==============================================================

// long double roundl(long double x)

// Return an integer value (represented as a long double) that is x

// rounded to nearest integer, halfway cases rounded away from

// zero.

//  if x>0   result = trunc(x+0.5)

//  if x<0   result = trunc(x-0.5)

//

//==============================================================

// double_extended

// if the exponent is > 1003e => 3F(true) = 63(decimal)

// we have a significand of 64 bits 1.63-bits.

// If we multiply by 2^63, we no longer have a fractional part

// So input is an integer value already.

// double

// if the exponent is >= 10033 => 34(true) = 52(decimal)

// 34 + 3ff = 433

// we have a significand of 53 bits 1.52-bits. (implicit 1)

// If we multiply by 2^52, we no longer have a fractional part

// So input is an integer value already.

// single

// if the exponent is > 10016 => 17(true) = 23(decimal)

// we have a significand of 24 bits 1.23-bits. (implicit 1)

// If we multiply by 2^23, we no longer have a fractional part

// So input is an integer value already.

.section .text

GLOBAL_LIBM_ENTRY(roundl)

{ .mfi

      getf.exp         rSignexp  = f8        // Get signexp, recompute if unorm

      fcvt.fx.trunc.s1 fXtruncInt  = f8      // Convert to int in significand

      addl             rBigexp = 0x1003e, r0 // Set exponent at which is integer

}

{ .mfi

      mov              rExpHalf    = 0x0FFFE // Form sign and exponent of 0.5

      fnorm.s1         fNormX  = f8          // Normalize input

      mov              rExpMask    = 0x1FFFF // Form exponent mask

}

;;

{ .mfi

      setf.exp         fHalf = rExpHalf      // Form 0.5

      fclass.m         p7,p0 = f8, 0x0b      // Test x unorm

      nop.i            0

}

;;

{ .mfb

      nop.m            0

      fclass.m         p6,p0 = f8, 0x1e3     // Test x natval, nan, inf

(p7)  br.cond.spnt     ROUND_UNORM           // Branch if x unorm

}

;;

ROUND_COMMON:

// Return here from ROUND_UNORM

{ .mfb

      nop.m            0

      fcmp.lt.s1       p8,p9 = f8, f0        // Test if x < 0

(p6)  br.cond.spnt     ROUND_SPECIAL         // Exit if x natval, nan, inf

}

;;

{ .mfi

      nop.m            0

      fcvt.xf          f8 = fXtruncInt        // Pre-Result if 0.5 <= |x| < 2^63

      nop.i            0

}

;;

{ .mfi

      and              rExp = rSignexp, rExpMask // Get biased exponent

      fmerge.s         fInc = fNormX, f1      // Form increment if |rem| >= 0.5

      nop.i            0

}

;;

{ .mmi

      cmp.lt           p6,p0 = rExp, rExpHalf // Is |x| < 0.5?

      cmp.ge           p7,p0 = rExp, rBigexp  // Is |x| >= 2^63?

      cmp.lt           p10,p0 = rExp, rExpHalf // Is |x| < 0.5?

}

;;

// We must correct result if |x| < 0.5, or |x| >= 2^63

.pred.rel "mutex",p6,p7

{ .mfi

      nop.m            0

(p6)  fmerge.s         f8 = fNormX, f0        // If |x| < 0.5, result sgn(x)*0

      nop.i            0

}

{ .mfb

(p7)  cmp.eq           p10,p0 = r0, r0        // Also turn on p10 if |x| >= 2^63

(p7)  fma.s0           f8 = fNormX, f1, f0    // If |x| >= 2^63, result x

(p10) br.ret.spnt      b0                     // Exit |x| < 0.5 or |x| >= 2^63

}

;;

// Here if 0.5 <= |x| < 2^63

{ .mfi

      nop.m            0

(p9)  fms.s1           fRem = fNormX, f1, f8  // Get remainder = x - trunc(x)

      nop.i            0

}

{ .mfi

      nop.m            0

(p8)  fms.s1           fRem = f8, f1, fNormX  // Get remainder = trunc(x) - x

      nop.i            0

}

;;

{ .mfi

      nop.m            0

      fcmp.ge.s1       p9,p0 = fRem, fHalf    // Test |rem| >= 0.5

      nop.i            0

}

;;

// If x < 0 and remainder <= -0.5, then subtract 1 from result

// If x > 0 and remainder >= +0.5, then add 1 to result

{ .mfb

      nop.m            0

(p9)  fma.s0           f8 = f8, f1, fInc

      br.ret.sptk      b0

}

;;

ROUND_SPECIAL:

// Here if x natval, nan, inf

{ .mfb

      nop.m            0

      fma.s0           f8 = f8, f1, f0

      br.ret.sptk      b0

}

;;

ROUND_UNORM:

// Here if x unorm

{ .mfi

      getf.exp         rSignexp  = fNormX     // Get signexp, recompute if unorm

      fcmp.eq.s0       p7,p0 = f8, f0         // Dummy op to set denormal flag

      nop.i            0

}

{ .mfb

      nop.m            0

      fcvt.fx.trunc.s1 fXtruncInt  = fNormX   // Convert to int in significand

      br.cond.sptk     ROUND_COMMON           // Return to main path

}

;;

GLOBAL_LIBM_END(roundl)

libm_alias_ldouble_other (round, round)