.file "ilogb.s"// Copyright (c) 2000 - 2003, Intel Corporation// All rights reserved.//// Contributed 2000 by the Intel Numerics Group, Intel Corporation//// Redistribution and use in source and binary forms, with or without// modification, are permitted provided that the following conditions are// met://// * Redistributions of source code must retain the above copyright// notice, this list of conditions and the following disclaimer.//// * Redistributions in binary form must reproduce the above copyright// notice, this list of conditions and the following disclaimer in the// documentation and/or other materials provided with the distribution.//// * The name of Intel Corporation may not be used to endorse or promote// products derived from this software without specific prior written// permission.// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL INTEL OR ITS// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY// OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY OR TORT (INCLUDING// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.//// Intel Corporation is the author of this code, and requests that all// problem reports or change requests be submitted to it directly at// 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, corrected error tag value.// 05/20/02 Cleaned up namespace and sf0 syntax// 01/20/03 Improved performance//// API//==============================================================// int ilogb( double x );//// Overview of operation//==============================================================// The ilogb function extracts the exponent of x as an integer// and returns it in r8//// ilogb is similar to logb but differs in the following ways://         +-inf//            ilogb: returns INT_MAX//             logb: returns +inf//         Nan  returns FP_LOGBNAN (which is either INT_MAX or INT_MIN)//            ilogb: returns INT_MAX (7fffffff)//             logb: returns QNAN (quietized SNAN)//         0    returns FP_ILOGB0 (which is either INT_MIN or -INT_MAX)//            ilogb: returns -INT_MAX (80000001)//             logb: 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, inputrExpBias            = r26rExpMask            = r27rSignexp_x          = r28rExp_x              = r29rIntMax             = r30rExp_2to64          = r31GR_SAVE_PFS         = r32rTrialResult        = r33GR_SAVE_B0          = r34GR_SAVE_GP          = r35GR_Parameter_X      = r36GR_Parameter_Y      = r37GR_Parameter_RESULT = r38GR_Parameter_TAG    = r39fTmp                = f9fNorm_x             = f10f2to64              = f11.section .textGLOBAL_LIBM_ENTRY(ilogb)// 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 = 157  // Error code      nop.i           0      br.cond.sptk    __libm_error_region     // Call error support};;GLOBAL_LIBM_END(ilogb)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        stfd [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        stfd [GR_Parameter_X] = f8            // STORE Parameter 1 on stack        add   GR_Parameter_RESULT = 0,GR_Parameter_Y    // Parameter 3 address        nop.b 0}{ .mib        stfd [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#