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Diffstat (limited to 'src/VBox/Runtime/common/math/expf.asm')
| -rw-r--r-- | src/VBox/Runtime/common/math/expf.asm | 151 |
1 files changed, 151 insertions, 0 deletions
diff --git a/src/VBox/Runtime/common/math/expf.asm b/src/VBox/Runtime/common/math/expf.asm new file mode 100644 index 00000000..81d12434 --- /dev/null +++ b/src/VBox/Runtime/common/math/expf.asm @@ -0,0 +1,151 @@ +; $Id: expf.asm $ +;; @file +; IPRT - No-CRT expf - AMD64 & X86. +; + +; +; Copyright (C) 2006-2023 Oracle and/or its affiliates. +; +; This file is part of VirtualBox base platform packages, as +; available from https://www.virtualbox.org. +; +; This program is free software; you can redistribute it and/or +; modify it under the terms of the GNU General Public License +; as published by the Free Software Foundation, in version 3 of the +; License. +; +; This program is distributed in the hope that it will be useful, but +; WITHOUT ANY WARRANTY; without even the implied warranty of +; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +; General Public License for more details. +; +; You should have received a copy of the GNU General Public License +; along with this program; if not, see <https://www.gnu.org/licenses>. +; +; The contents of this file may alternatively be used under the terms +; of the Common Development and Distribution License Version 1.0 +; (CDDL), a copy of it is provided in the "COPYING.CDDL" file included +; in the VirtualBox distribution, in which case the provisions of the +; CDDL are applicable instead of those of the GPL. +; +; You may elect to license modified versions of this file under the +; terms and conditions of either the GPL or the CDDL or both. +; +; SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0 +; + + +%define RT_ASM_WITH_SEH64 +%include "iprt/asmdefs.mac" +%include "iprt/x86.mac" + + +BEGINCODE + +extern NAME(RT_NOCRT(feraiseexcept)) + +;; +; Compute the e (2.7182818...) to the power of rd. +; @returns st(0) / xmm0 +; @param rd [xSP + xCB*2] / xmm0 +RT_NOCRT_BEGINPROC expf + push xBP + SEH64_PUSH_xBP + mov xBP, xSP + SEH64_SET_FRAME_xBP 0 + sub xSP, 20h + SEH64_ALLOCATE_STACK 20h + SEH64_END_PROLOGUE + + ; + ; Load the input into st0. + ; +%ifdef RT_ARCH_AMD64 + movss [xBP - 10h], xmm0 + fld dword [xBP - 10h] +%else + fld dword [xBP + xCB*2] +%endif + + ; + ; Weed out non-normal values. + ; + fxam + fnstsw ax + mov cx, ax + and ax, X86_FSW_C3 | X86_FSW_C2 | X86_FSW_C0 + cmp ax, X86_FSW_C2 ; Normal finite number (excluding zero) + je .finite + cmp ax, X86_FSW_C3 ; Zero + je .zero + cmp ax, X86_FSW_C3 | X86_FSW_C2 ; Denormals + je .finite + cmp ax, X86_FSW_C0 | X86_FSW_C2 ; Infinity. + je .inf + jmp .nan + +.finite: + ; + ; Convert to power of 2 and it'll be the same as exp2. + ; + fldl2e ; -> st0=log2(e); st1=input + fmulp ; -> st0=input*log2(e) + + ; + ; Split the job in two on the fraction and integer input parts. + ; + fld st0 ; Push a copy of the input on the stack. + frndint ; st0 = (int)(input*log2(e)) + fsub st1, st0 ; st1 = input*log2(e) - (int)input*log2(e); i.e. st1 = fraction, st0 = integer. + fxch ; st0 = fraction, st1 = integer. + + ; 1. Calculate on the fraction. + f2xm1 ; st0 = 2**fraction - 1.0 + fld1 + faddp ; st0 = 2**fraction + + ; 2. Apply the integer power of two. + fscale ; st0 = result; st1 = integer part of input. + fstp st1 ; st0 = result; no st1. + + ; + ; Return st0. + ; +.return_val: +%ifdef RT_ARCH_AMD64 + fstp dword [xBP - 10h] + movss xmm0, [xBP - 10h] +%endif +.return: + leave + ret + + ; + ; +/-0.0: Return +1.0 + ; +.zero: + ffreep st0 + fld1 + jmp .return_val + + ; + ; -Inf: Return +0.0. + ; +Inf: Return +Inf. Join path with NaN. + ; +.inf: + test cx, X86_FSW_C1 ; sign bit + jz .nan + ffreep st0 + fldz + jmp .return_val + + ; + ; NaN: Return the input NaN value as is, if we can. + ; +.nan: +%ifdef RT_ARCH_AMD64 + ffreep st0 +%endif + jmp .return +ENDPROC RT_NOCRT(expf) + |