Xref: utzoo comp.lang.c:16358 comp.sys.m68k:1103 comp.sys.intel:704
Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!sharkey!atanasoff!hascall
From: hascall@atanasoff.cs.iastate.edu (John Hascall)
Newsgroups: comp.lang.c,comp.sys.m68k,comp.sys.intel
Subject: Re: Efficientness of Compiler Generated Code
Keywords: bit-fields operations; HLL instructions; m68000; i8086; C
Message-ID: <817@atanasoff.cs.iastate.edu>
Date: 18 Feb 89 18:24:36 GMT
References: <7756@ihlpf.ATT.COM>
Reply-To: hascall@atanasoff.cs.iastate.edu (John Hascall)
Distribution: usa
Organization: Iowa State U. Computer Science Department, Ames, IA
Lines: 17

In article <7756@ihlpf.ATT.COM> pcl@ihlpf.UUCP (pcl) writes:
>I wonder if any microprocessor supports HLL instruction such as:
>
>incbf memloc,bf_offset,bf_len		/* increment a bit field */
>setbf memloc,bf_offset,bf_len,immed	/* increment a bit field */
                                           ^^^^ set?

   A VAX (I guess we can consider a uVAX a uProcessor :-) could
   do something like this for "incbf":

      EXTV  #pos,#bits,base,temp      ; extract and extend base<pos:pos+bits-1>
      INCL  temp                      ; increment
      INSV  temp,#pos,#bits,base      ; insert into base<pos:pos+bits-1>

      and of course, just INSV can be used for "setbf".

John Hascall / ISU Comp Center