glibc/sysdeps/ia64/fpu/s_significandf.S

.file "significandf.s"


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//
// History
//==============================================================
// 02/02/00 Initial version
// 02/03/00 Modified to improve speed
// 05/31/00 Fixed bug when x a double-extended denormal
// 05/20/02 Cleaned up namespace and sf0 syntax
// 02/10/03 Reordered header: .section, .global, .proc, .align
//
// API
//==============================================================
// float significandf(float x)
// Overview of operation
//==============================================================
// If x = sig * 2**n with 1 <= sig < 2
// significandf returns sig
//
// predicate registers used:
// p6, p7
//
// floating-point registers used:
// f8, f9, f10

.section .text
GLOBAL_LIBM_ENTRY(significandf)

// qnan snan inf norm     unorm 0 -+
// 1    1    1   0        0     1 11

// f10 gets f8(sign) with f1(exp,significand)
{ .mfi
      nop.m 999
      fmerge.s       f10 = f8,f1
      nop.i 999
}
{ .mfi
      nop.m 999
      fnorm.s0          f9  = f8
      nop.i 999 ;;
}

// Test for denormal input
{ .mfi
      nop.m 999
      fclass.m.unc   p7,p0 = f8, 0x0b
      nop.i 999 ;;
}

// p6 = TRUE ==> x is not (nan,inf,0)
//               return sign(f8) exp(f1) significand(f8)
// else          x is (nan,inf,0)
//               return sign(f8) exp(f8) significand(f8), normalized.
{ .mfi
      nop.m 999
      fclass.m.unc   p0,p6 = f8, 0xe7
      nop.i 999 ;;
}

{ .mmb
      nop.m 999
      nop.m 999
(p7)  br.cond.spnt SIGNIFICAND_DENORM ;; // Branch if x denormal
}

{ .mfi
      nop.m 999
(p6)  fmerge.se      f8 = f10,f8
      nop.i 999 ;;
}

{ .mfb
      nop.m 999
      fnorm.s.s0        f8 = f8
      br.ret.sptk    b0 ;;
}

SIGNIFICAND_DENORM:
// Here if x denorm
{ .mfi
      nop.m 999
      fmerge.se      f8 = f10,f9
      nop.i 999 ;;
}

// Check if fnorm(x) still denormal, means x double-extended denormal
{ .mfi
      nop.m 999
      fclass.m.unc   p7,p0 = f9, 0x0b
      nop.i 999 ;;
}

// This will be the final result unless x double-extended denormal
{ .mfi
      nop.m 999
      fnorm.s.s0        f8 = f8
      nop.i 999 ;;
}

// If x double-extended denorm, then significand ok, but must merge in
//    correct signexp
{ .mfi
      nop.m 999
(p7)  fmerge.se      f8 = f10,f8
      nop.i 999 ;;
}

// Final normalization if x double-extended denorm
{ .mfb
      nop.m 999
(p7)  fnorm.s.s0        f8 = f8
      br.ret.sptk    b0 ;;
}

GLOBAL_LIBM_END(significandf)