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Diffstat (limited to 'sysdeps/ia64/fpu/libm_frexp.S')
| -rw-r--r-- | sysdeps/ia64/fpu/libm_frexp.S | 209 |
1 files changed, 209 insertions, 0 deletions
diff --git a/sysdeps/ia64/fpu/libm_frexp.S b/sysdeps/ia64/fpu/libm_frexp.S new file mode 100644 index 0000000000..51bb268dda --- /dev/null +++ b/sysdeps/ia64/fpu/libm_frexp.S @@ -0,0 +1,209 @@ +.file "libm_frexp.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 +//============================================================== +// 02/02/00 Initial version +// 03/20/00 Improved speed +// 06/01/00 Fixed bug when x a double-extended denormal +// 12/08/00 Corrected label on .endp +// 01/23/02 Added handling for int 32 or 64 bits +// 05/20/02 Cleaned up namespace and sf0 syntax +// 02/10/03 Reordered header: .section, .global, .proc, .align +// +// API +//============================================================== +// double __libm_frexp(double x, int* y, int int_type) +// input floating point f8, pointer to y (r33), int int_type (r34) +// output floating point f8, returns the fraction of x, 0.5 <= fraction < 1.0 +// output int* y, returns the true exponent of x +// +// int_type = 0 if int is 32 bits +// int_type = 1 if int is 64 bits +// +// int* y is returned as a 32 bit integer if int_type = 0 +// int* y is returned as a 64 bit integer if int_type = 1 +// +// Overview of operation +//============================================================== +// break a floating point x number into fraction and an exponent +// The fraction is returned as a double +// The exponent is returned as an integer pointed to by y +// This is a true (not a biased exponent) but 0fffe is subtracted +// as a bias instead of 0xffff. This is because the fraction returned +// is between 0.5 and 1.0, not the expected IEEE range. +// +// The fraction is 0.5 <= fraction < 1.0 +// +// Registers used +//============================================================== +// +// general registers: +// r14 exponent bias for x negative +// r15 exponent bias for x positive +// r16 signexp of x +// r17 exponent mask +// r18 exponent of x +// r19 exponent result +// r20 signexp of 2^64 +// r32 on input contains the 64-bit IEEE double that is in f8 +// r33 on input pointer to 32-bit or 64-bit integer for exponent +// r34 on input contains 0 if output int is 32 bits, else output int is 64 bits +// +// predicate registers: +// p6 set if x is Nan, zero, or infinity +// p7 set if x negative +// p8 set if x positive +// p9 set if x double-extended denormal +// p10 set if int_type = 0, 32-bit integer +// p11 set if int_type = 1, 64-bit integer +// +// floating-point registers: +// f8 input, output +// f9 normalized x +// f10 signexp for significand result for x positive +// f11 signexp for significand result for x negative +// f12 2^64 + +.section .text +GLOBAL_LIBM_ENTRY(__libm_frexp) + +// Set signexp for significand result for x>0 +// If x is a NaN, zero, or infinity, return it. +// Put 0 in the int pointer. +// x NAN, ZERO, INFINITY? +// Set signexp for significand result for x<0 +{ .mfi + mov r15 = 0x0fffe + fclass.m p6,p7 = f8, 0xe7 + mov r14 = 0x2fffe +} +// Form signexp of 2^64 in case x double-extended denormal +// Save the normalized value of input in f9 +// The normalization also sets fault flags and takes faults if necessary +{ .mfi + mov r20 = 0x1003f + fnorm.s0 f9 = f8 + nop.i 999 ;; +} + +// Move signexp for significand result for x>0 to FP reg +// Form 2^64 in case x double-extended denormal +{ .mmi + setf.exp f10 = r15 + setf.exp f12 = r20 + nop.i 999 ;; +} + +// Move signexp for significand result for x<0 to FP reg +// p7 if x<0, else p8 +// If x=0,nan,inf, set p10 if output int to be 32 bits, or set p11 if 64 bits +{ .mfi + setf.exp f11 = r14 +(p7) fcmp.lt.s0 p7,p8 = f8,f0 +(p6) cmp.eq.unc p10,p11 = r34, r0 ;; +} + +// If x NAN, ZERO, INFINITY, set *y=0 and exit +{ .mmb +(p10) st4 [r33] = r0 // Store *y=0 as 32-bit integer +(p11) st8 [r33] = r0 // Store *y=0 as 64-bit integer +(p6) br.ret.spnt b0 ;; +} + +// Form exponent mask +// Test for fnorm(x) denormal, means x double-extended denormal +{ .mfi + mov r17 = 0x1ffff + fclass.m p9,p0 = f9, 0x0b + nop.i 999 ;; +} + +// If x double-extended denormal add 64 to exponent bias for scaling +// If x double-extended denormal multiply x * 2^64 which is normal +// Set p10 if output int to be 32 bits, or set p11 if 64 bits +{ .mfi +(p9) add r15 = 64, r15 +(p9) fmpy.s0 f9 = f9, f12 + cmp.eq p10,p11 = r34, r0 ;; +} + +// true exponent stored to int pointer +// the bias is treated as 0xfffe instead of +// normal 0xffff because we want the significand +// to be in the range <=0.5 sig < 1.0 +// Store the value of the exponent at the pointer in r33 + +// If x>0 form significand result +{ .mfi + nop.m 999 +(p8) fmerge.se f8 = f10,f9 + nop.i 999 ;; +} + +// Get signexp of normalized x +// If x<0 form significand result +{ .mfi + getf.exp r16 = f9 +(p7) fmerge.se f8 = f11,f9 + nop.i 999 ;; +} + +// Get exp of normalized x +// Subtract off bias to get true exponent of x +{ .mmi + and r18 = r17,r16 ;; + sub r19 = r18,r15 + nop.i 999 ;; +} + +// Store int *y as a 32-bit integer +// Make the value a double +{ .mfi +(p10) st4 [r33] = r19 // Store *y as 32-bit integer + fnorm.d.s0 f8 = f8 + nop.i 999 +} +{ .mfb +(p11) st8 [r33] = r19 // Store *y as 64-bit integer + nop.f 999 + br.ret.sptk b0 ;; +} + +GLOBAL_LIBM_END(__libm_frexp) |