.file "ilogbl.s"

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

// All rights reserved.

//

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

//

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

//

// History

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

// 02/03/00 Initial version

// 05/26/00 Fix bug when x a double-extended denormal;

//          if x=0 call error routine, per C9X

// 08/15/00 Bundle added after call to __libm_error_support to properly

//          set [the previously overwritten] GR_Parameter_RESULT.

// 01/20/01 Fixed result for x=0

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

// 01/20/03 Improved performance

//

// API

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

// int ilogbl( long double x );

//

// Overview of operation

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

// The ilogbl function extracts the exponent of x as an integer

// and returns it in r8

//

// ilogbl is similar to logbl but differs in the following ways:

//         +-inf

//            ilogbl: returns INT_MAX

//             logbl: returns +inf

//         Nan  returns FP_LOGBNAN (which is either INT_MAX or INT_MIN)

//            ilogbl: returns INT_MAX (7fffffff)

//             logbl: returns QNAN (quietized SNAN)

//         0    returns FP_ILOGB0 (which is either INT_MIN or -INT_MAX)

//            ilogbl: returns -INT_MAX (80000001)

//             logbl: returns -inf, raises the divide-by-zero exception,

//                   and calls libm_error_support to set domain error

//

// Registers used

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

// general registers used:

// r26 -> r39

// r36 -> r39 used as parameters to error path

//

// predicate registers used:

// p6 -> p10

// floating-point registers used:

// f9, f10, f11

// f8, input

rExpBias            = r26

rExpMask            = r27

rSignexp_x          = r28

rExp_x              = r29

rIntMax             = r30

rExp_2to64          = r31

GR_SAVE_PFS         = r32

rTrialResult        = r33

GR_SAVE_B0          = r34

GR_SAVE_GP          = r35

GR_Parameter_X      = r36

GR_Parameter_Y      = r37

GR_Parameter_RESULT = r38

GR_Parameter_TAG    = r39

fTmp                = f9

fNorm_x             = f10

f2to64              = f11

.section .text

GLOBAL_LIBM_ENTRY(__ieee754_ilogbl)

// X NORMAL

// TrueExp_x = exp(f8) - 0xffff

// r8 = TrueExp_x

{ .mfi

      getf.exp        rSignexp_x = f8

      fclass.m        p8,p0 = f8, 0x0b   // Test for x unorm

      mov             rExpBias = 0xffff  // Exponent bias

}

{ .mfi

      nop.m           0

      fnorm.s1        fNorm_x = f8

      mov             rExpMask = 0x1ffff // Exponent mask

}

;;

// Form signexp of 2^64 in case need to scale denormal

{ .mfb

      mov             rExp_2to64 = 0x1003f

      fclass.m        p6,p9 = f8, 0x1e3  // Test x natval, nan, inf

(p8)  br.cond.spnt    ILOGB_DENORM       // Branch if x unorm

}

;;

ILOGB_COMMON:

// Return here from ILOGB_DENORM

{ .mfi

      and             rExp_x = rSignexp_x, rExpMask // Get biased exponent

      fclass.m        p7,p10 = f8, 0x07   // Test x zero

      nop.i           0

}

{ .mlx

      nop.m           0

      movl            rIntMax = 0x000000007fffffff // Form INT_MAX

}

;;

.pred.rel "mutex",p6,p9

{ .mfi

(p9)  sub             r8 = rExp_x, rExpBias // Get true exponent for normal path

(p6)  fma.s0          fTmp = f8, f8, f0     // Dummy to set Invalid flag

(p6)  mov             r8 = rIntMax          // If nan, inf, return INT_MAX

}

{ .mbb

      nop.m           0

(p7)  br.cond.spnt    ILOGB_ZERO            // Branch if x zero

(p10) br.ret.sptk     b0                    // Exit if x not zero

}

;;

ILOGB_DENORM:

// Form 2^64 in case need to scale denormal

// Check to see if double-extended denormal

{ .mfi

      setf.exp        f2to64 = rExp_2to64

      fclass.m        p8,p0 = fNorm_x, 0x0b

      nop.i           0

}

;;

{ .mfi

      nop.m           0

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

      nop.i           0

}

;;

// If double-extended denormal add 64 to exponent bias for scaling

// If double-extended denormal form x * 2^64 which is normal

{ .mfi

(p8)  add             rExpBias = 64, rExpBias

(p8)  fmpy.s1         fNorm_x = fNorm_x, f2to64

      nop.i           0

}

;;

// Logic is the same as normal path but use normalized input

{ .mib

      getf.exp        rSignexp_x = fNorm_x

      nop.i           0

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

}

;;

ILOGB_ZERO:

// Here if x zero

// Return INT_MIN, call error support

{ .mlx

      alloc           r32=ar.pfs,1,3,4,0

      movl            rTrialResult = 0x0000000080000000

}

{ .mib

      mov             GR_Parameter_TAG = 156  // Error code

      nop.i           0

      br.cond.sptk    __libm_error_region     // Call error support

}

;;

GLOBAL_LIBM_END(__ieee754_ilogbl)

LOCAL_LIBM_ENTRY(__libm_error_region)

.prologue

{ .mfi

        add   GR_Parameter_Y=-32,sp           // Parameter 2 value

        nop.f 0

.save   ar.pfs,GR_SAVE_PFS

        mov  GR_SAVE_PFS=ar.pfs               // Save ar.pfs

}

{ .mfi

.fframe 64

        add sp=-64,sp                         // Create new stack

        nop.f 0

        mov GR_SAVE_GP=gp                     // Save gp

};;

{ .mmi

        stfe [GR_Parameter_Y] = f0,16         // STORE Parameter 2 on stack

        add GR_Parameter_X    = 16,sp         // Parameter 1 address

.save   b0, GR_SAVE_B0

        mov GR_SAVE_B0=b0                     // Save b0

};;

.body

{ .mib

        stfe [GR_Parameter_X] = f8            // STORE Parameter 1 on stack

        add   GR_Parameter_RESULT = 0,GR_Parameter_Y    // Parameter 3 address

        nop.b 0

}

{ .mib

        stfe [GR_Parameter_Y] = f9            // Store Parameter 3 on stack

        add   GR_Parameter_Y = -16,GR_Parameter_Y

        br.call.sptk b0=__libm_error_support# // Call error handling function

};;

{ .mmi

        add   GR_Parameter_RESULT = 48,sp

        nop.m 0

        nop.i 0

};;

{ .mmi

        mov   r8 = rTrialResult

.restore sp

        add   sp = 64,sp                       // Restore stack pointer

        mov   b0 = GR_SAVE_B0                  // Restore return address

};;

{ .mib

        mov   gp = GR_SAVE_GP                  // Restore gp

        mov   ar.pfs = GR_SAVE_PFS             // Restore ar.pfs

        br.ret.sptk   b0

};;

LOCAL_LIBM_END(__libm_error_region)

.type   __libm_error_support#,@function

.global __libm_error_support#