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authorJakub Jelinek <jakub@redhat.com>2007-07-12 18:26:36 +0000
committerJakub Jelinek <jakub@redhat.com>2007-07-12 18:26:36 +0000
commit0ecb606cb6cf65de1d9fc8a919bceb4be476c602 (patch)
tree2ea1f8305970753e4a657acb2ccc15ca3eec8e2c /sysdeps/ia64/fpu/libm_frexpf.S
parent7d58530341304d403a6626d7f7a1913165fe2f32 (diff)
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+.file "libm_frexpf.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
+//==============================================================
+// float __libm_frexpf(float 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 float
+// 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 32-bit IEEE float 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_frexpf)
+
+// 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 float
+{ .mfi
+(p10)   st4         [r33] = r19        // Store *y as 32-bit integer
+        fnorm.s.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_frexpf)