From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-3.0 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,RCVD_IN_MSPIKE_H3, RCVD_IN_MSPIKE_WL autolearn=ham autolearn_force=no version=3.4.2 Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by inbox.vuxu.org (OpenSMTPD) with SMTP id b9dc6a7b for ; Thu, 16 Jan 2020 04:30:21 +0000 (UTC) Received: (qmail 7260 invoked by uid 550); 16 Jan 2020 04:30:20 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Reply-To: musl@lists.openwall.com Received: (qmail 7226 invoked from network); 16 Jan 2020 04:30:19 -0000 X-Authentication-Warning: key0.esi.com.au: damianm owned process doing -bs Date: Thu, 16 Jan 2020 15:30:03 +1100 (AEDT) From: Damian McGuckin To: musl@lists.openwall.com Message-ID: User-Agent: Alpine 2.02 (LRH 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; format=flowed; charset=US-ASCII Subject: [musl] Considering x86-64 fenv.s to C I was just looking at fenv.s in x86-64 with a view to doing this as C-code with some __asm__. I have limited experience with playing with this stuff in an SSE-only environment, i.e. no 80-bit floats. Before I attempt anything, I need to expand my knowledge. My observations on musl-1.1.24/src/fenv/x86_64/fenv.s * feclearexcept considers both the X87 status word and the SSE MXCSR * feraiseexcept ignores the X87 status word and considers only the SSE MXCSR * fetesteexcept considers both the X87 status word and the SSE MXCSR * fesetround considers both the X87 control word and the SSE MXCSR * fegetround ignores the X87 control word and considers only the SSE MXCSR Why is the X87 component of the FPU control/status sometimes ignored and sometimes not? Does the X87 control or status bits automatically flow through to the equivalent stuff in the SSE or vica-versa? I assume that 'fwait' is irrelevant and unnecessary, even if one is using the x87 FPU? Regards - Damian Pacific Engineering Systems International, 277-279 Broadway, Glebe NSW 2037 Ph:+61-2-8571-0847 .. Fx:+61-2-9692-9623 | unsolicited email not wanted here Views & opinions here are mine and not those of any past or present employer