3 // Copyright (c) 2000, 2001, Intel Corporation
4 // All rights reserved.
6 // Contributed 2/2/2000 by John Harrison, Ted Kubaska, Bob Norin, Shane Story,
7 // and Ping Tak Peter Tang of the Computational Software Lab, Intel Corporation.
11 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
12 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
13 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
14 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL INTEL OR ITS
15 // CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
16 // EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
17 // PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
18 // PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
19 // OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY OR TORT (INCLUDING
20 // NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
21 // SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
23 // Intel Corporation is the author of this code, and requests that all
24 // problem reports or change requests be submitted to it directly at
25 // http://developer.intel.com/opensource.
28 //==============================================================
29 // 2/03/00 Initial version
30 // 5/26/00 Fix bug when x a double-extended denormal;
31 // if x=0 call error routine, per C9X
32 // 8/15/00 Bundle added after call to __libm_error_support to properly
33 // set [the previously overwritten] GR_Parameter_RESULT.
34 // 1/20/01 Fixed result for x=0, corrected error tag value.
44 //==============================================================
45 // int = ilogb(double)
47 // Overview of operation
48 //==============================================================
49 // ilogb computes log2(x) as an int
50 // and returns it in r8
52 // ilogb is similar to logb but differs in the following ways:
54 // ilogb: returns INT_MAX
56 // Nan returns FP_ILOGBNAN (which is either INT_MAX or INT_MIN)
57 // ilogb: returns INT_MAX (7fffffff)
58 // logb: returns QNAN (quieted SNAN)
59 // 0 returns FP_ILOGB0 (which is either INT_MIN or -INT_MAX)
60 // ilogb: returns INT_MIN (80000000)
64 //==============================================================
66 // general local registers:
69 // r38 -> r41 used as parameters to error path
71 // predicate registers used:
77 // floating-point registers used:
80 #include "libm_support.h"
87 GR_Parameter_RESULT = r40
88 GR_Parameter_TAG = r41
97 // Form signexp of 2^64 in case need to scale denormal
99 alloc r32=ar.pfs,1,5,4,0
100 (p0) mov r37 = 0x1003f
101 (p0) fnorm f9 = f8 ;;
104 // Form 2^64 in case need to scale denormal
106 (p0) setf.exp f10 = r37
107 (p0) fclass.m.unc p7, p8 = f8, 0xe3
108 (p0) mov r34 = 0xffff ;;
111 // qnan snan inf norm unorm 0 -+
114 // X ZERO, returns INT_MIN
115 // X INF or NAN, returns INT_MAX
118 (p0) mov r35 = 0x1ffff
119 (p8) fclass.m.unc p6, p8 = f8, 0x07
124 (p7) movl r8 = 0x000000007fffffff ;;
130 (p6) br.cond.spnt L(ILOGB_ZERO) ;;
136 (p8) fclass.m.unc p9, p0 = f9, 0x0b
141 // X NORMAL returns true exponent
144 (p8) getf.exp r33 = f9
148 // If denormal add 64 to exponent bias for scaling
150 (p9) add r34 = 64, r34
152 (p9) br.cond.spnt L(ILOGB_DENORM) ;;
156 (p8) and r36 = r35, r33
162 (p8) sub r8 = r36, r34
164 (p0) br.ret.sptk b0 ;;
168 // Here if x denormal
169 // Form x * 2^64 which is normal
170 // Return to common code
174 br.cond.sptk L(ILOGB_COMMON) ;;
178 // return INT_MIN, call error support
181 mov GR_Parameter_TAG = 157
182 (p6) movl r33 = 0x0000000080000000 ;;
185 ASM_SIZE_DIRECTIVE(ilogb)
187 .proc __libm_error_region
191 add GR_Parameter_Y=-32,sp // Parameter 2 value
193 .save ar.pfs,GR_SAVE_PFS
194 mov GR_SAVE_PFS=ar.pfs // Save ar.pfs
198 add sp=-64,sp // Create new stack
200 mov GR_SAVE_GP=gp // Save gp
203 stfd [GR_Parameter_Y] = FR_Y,16 // Save Parameter 2 on stack
204 add GR_Parameter_X = 16,sp // Parameter 1 address
206 mov GR_SAVE_B0=b0 // Save b0
210 stfd [GR_Parameter_X] = FR_X // Store Parameter 1 on stack
211 add GR_Parameter_RESULT = 0,GR_Parameter_Y
212 nop.b 0 // Parameter 3 address
215 stfd [GR_Parameter_Y] = FR_RESULT // Store Parameter 3 on stack
216 add GR_Parameter_Y = -16,GR_Parameter_Y
217 br.call.sptk b0=__libm_error_support# // Call error handling function
222 add GR_Parameter_RESULT = 48,sp
225 mov r8 = r33 // Store result
227 add sp = 64,sp // Restore stack pointer
228 mov b0 = GR_SAVE_B0 // Restore return address
231 mov gp = GR_SAVE_GP // Restore gp
232 mov ar.pfs = GR_SAVE_PFS // Restore ar.pfs
233 br.ret.sptk b0 // Return
236 .endp __libm_error_region
237 ASM_SIZE_DIRECTIVE(__libm_error_region)
239 .type __libm_error_support#,@function
240 .global __libm_error_support#