Xref: utzoo comp.lang.c++:2209 comp.lang.c:14578 comp.lang.misc:2308 Path: utzoo!utgpu!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!unmvax!pprg.unm.edu!hc!lll-winken!arisia!quintus!ok From: ok@quintus.uucp (Richard A. O'Keefe) Newsgroups: comp.lang.c++,comp.lang.c,comp.lang.misc Subject: Re: Assembly or .... Message-ID: <818@quintus.UUCP> Date: 6 Dec 88 08:29:45 GMT References: <1388@aucs.UUCP> <707@ethz.UUCP> Sender: news@quintus.UUCP Reply-To: ok@quintus.UUCP (Richard A. O'Keefe) Organization: Quintus Computer Systems, Inc. Lines: 20 In article <707@ethz.UUCP> pasche@bernina.UUCP (Stephan Paschedag) writes: >In article <1388@aucs.UUCP> 861087p@aucs.UUCP (A N D R E A S) writes: >>I've been told also that there are some low-level operations >>that you just can't do in C or any other high level language. >for example : I don't know a high-level language where you have control of > the CPU status flags. These can be very useful for some (a) BLISS, PL/360, most such MOHLLs. (b) C with "asm" or "inline" can be made to generate any instruction. (c) A high-level language which is not tied to a specific machine can't provide a way of getting at the condition codes/carry/overflow flag for the simple reason that there are machines (MIPS, MC88000) which haven't got any. > applications. One example is an operation you need for a > fft program. Bit reversal for an FFT program is best done with a table lookup. On most machines the floating-point operations will swamp the bit reversal, so you don't need the machine-specific loop. On a high- performance machine (e.g. MIPS) the bit-at-a-time loop will be killingly slow, compared with a table lookup.