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+.file "logb.s"
+
+// Copyright (c) 2000, 2001, Intel Corporation
+// All rights reserved.
+// 
+// Contributed 2/2/2000 by John Harrison, Ted Kubaska, Bob Norin, Shane Story,
+// and Ping Tak Peter Tang of the Computational Software Lab, Intel Corporation.
+// 
+// WARRANTY DISCLAIMER
+// 
+// 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://developer.intel.com/opensource.
+//
+// History
+//==============================================================
+// 2/02/00  Initial version
+// 2/16/00  Modified to conform to C9X 
+// 3/16/00  Improved speed
+// 4/04/00  Unwind support added
+// 5/30/00  Fixed bug when x double-extended denormal
+// 8/15/00  Bundle added after call to __libm_error_support to properly
+//          set [the previously overwritten] GR_Parameter_RESULT.
+//
+// API
+//==============================================================
+// double logb( double x);
+//
+// Overview of operation
+//==============================================================
+// The logb function extracts the exponent of x as an integer in 
+// floating-point format. 
+// logb computes log2 of x as a double
+//
+// logb is similar to ilogb 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: 
+// ar.pfs r32 
+// r33 -> r37
+// r38 -> r41 used as parameters to error path
+//
+// predicate registers used: 
+// p6, p7, p8
+// floating-point registers used: 
+// f9, f10, f11
+// f8, input
+
+#include "libm_support.h"
+
+GR_SAVE_B0          = r34
+GR_SAVE_GP          = r35
+GR_SAVE_PFS         = r32
+
+GR_Parameter_X      = r38
+GR_Parameter_Y      = r39
+GR_Parameter_RESULT = r40
+
+.align 32
+.global logb#
+
+.section .text
+.proc  logb#
+.align 32
+
+
+logb: 
+
+// qnan snan inf norm     unorm 0 -+
+// 0    0    0   0        1     0 11
+// 0                      b
+{ .mfi
+      alloc          r32=ar.pfs,1,5,4,0
+(p0)  fclass.m.unc  p8,p0 = f8, 0x0b
+      nop.i 999
+}
+// X NORMAL
+// r37 = exp(f8) - - 0xffff
+// sig(f8) = r37
+// f8 = convert_to_fp (sig))
+{ .mfi
+(p0)  getf.exp      r35 = f8
+(p0)  fnorm         f10=f8
+      nop.i 999 ;;
+}
+
+// qnan snan inf norm     unorm 0 -+
+// 1    1    1   0        0     0 11
+// e                      3
+{ .mmf
+(p0)  mov      r33 = 0xffff
+(p0)  mov      r34 = 0x1ffff
+(p0)  fclass.m.unc  p6,p0 = f8, 0xe3 ;;
+}
+
+{ .mfb
+(p0)  and           r36 = r35, r34
+(p0)  fclass.m.unc  p7,p0 = f8, 0x07
+(p8)  br.cond.spnt  L(LOGB_DENORM) ;;
+}
+
+{ .mib
+(p0)  sub           r37 = r36, r33
+      nop.i 999
+(p6)  br.cond.spnt  L(LOGB_NAN_INF) ;;
+}
+
+{ .mib
+(p0)  setf.sig      f9  = r37
+      nop.i 999
+(p7)  br.cond.spnt  L(LOGB_ZERO) ;;
+}
+
+{ .mfi
+      nop.m 999
+(p0)  fcvt.xf       f10 = f9
+      nop.i 999 ;;
+}
+
+{ .mfb
+      nop.m 999
+(p0)  fnorm.d       f8 = f10
+(p0)  br.ret.sptk    b0 ;;
+}
+
+L(LOGB_DENORM):
+// Form signexp of 2^64 in case need to scale denormal
+// Check to see if double-extended denormal
+{ .mfi
+(p0)  mov r38 = 0x1003f
+(p0)  fclass.m.unc  p8,p0 = f10, 0x0b
+      nop.i 999 ;;
+}
+
+// Form 2^64 in case need to scale denormal
+{ .mfi
+(p0)  setf.exp f11 = r38
+      nop.f 999
+      nop.i 999 ;;
+}
+
+// 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 r33 = 64, r33
+(p8)  fmpy f10 = f10, f11    
+      nop.i 999 ;;
+}
+
+// Logic is the same as normal path but use normalized input
+{ .mmi
+(p0)  getf.exp      r35 = f10 ;;
+      nop.m 999
+      nop.i 999 ;;
+}
+
+{ .mmi
+(p0)  and           r36 = r35, r34 ;;
+(p0)  sub           r37 = r36, r33
+      nop.i 999 ;;
+}
+
+{ .mmi
+(p0)  setf.sig      f9  = r37
+      nop.m 999
+      nop.i 999 ;;
+}
+
+{ .mfi
+      nop.m 999
+(p0)  fcvt.xf       f10 = f9
+      nop.i 999 ;;
+}
+
+{ .mfb
+      nop.m 999
+(p0)  fnorm.d       f8 = f10
+(p0)  br.ret.sptk    b0 ;;
+}
+
+L(LOGB_NAN_INF): 
+
+// X NAN or INFINITY, return f8 * f8
+{ .mfb
+      nop.m 999
+(p0)  fma.d      f8= f8,f8,f0
+(p0)  br.ret.sptk   b0 ;;
+}
+
+.endp logb#
+ASM_SIZE_DIRECTIVE(logb)
+
+// Stack operations when calling error support.
+//       (1)               (2)                          (3) (call)              (4)
+//   sp   -> +          psp -> +                     psp -> +                   sp -> +
+//           |                 |                            |                         |
+//           |                 | <- GR_Y               R3 ->| <- GR_RESULT            | -> f8
+//           |                 |                            |                         |
+//           | <-GR_Y      Y2->|                       Y2 ->| <- GR_Y                 |
+//           |                 |                            |                         |
+//           |                 | <- GR_X               X1 ->|                         |
+//           |                 |                            |                         |
+//  sp-64 -> +          sp ->  +                     sp ->  +                         +
+//    save ar.pfs          save b0                                               restore gp
+//    save gp                                                                    restore ar.pfs
+
+
+
+.proc __libm_error_region
+__libm_error_region:
+L(LOGB_ZERO): 
+.prologue
+
+// f9  = |f8|
+// f10 = -f9 = -|f8|
+// f9  = 1.0/f10 = -1.0/-|f8|
+
+{ .mfi 
+      mov           r41 = 151      // Error code
+(p0)  fmerge.s      f9 = f0,f8
+      nop.i 999
+}
+;;
+
+
+{ .mfi
+      nop.m 999
+      fmerge.ns     f10 = f0,f9
+      nop.i 999
+}
+;;
+
+// (1)
+{ .mfi
+        add   GR_Parameter_Y=-32,sp             // Parameter 2 value
+        frcpa         f9,p6 = f1,f10
+.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
+};;
+
+
+// (2)
+{ .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
+// (3)
+{ .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
+        nop.m 0
+        nop.m 0
+        add   GR_Parameter_RESULT = 48,sp
+};;
+
+// (4)
+{ .mmi
+        ldfd  f8 = [GR_Parameter_RESULT]       // Get return result off stack
+.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
+};;
+
+.endp __libm_error_region
+ASM_SIZE_DIRECTIVE(__libm_error_region)
+
+.type   __libm_error_support#,@function
+.global __libm_error_support#