Path: utzoo!attcan!uunet!yale!husc6!purdue!spaf
From: spaf@cs.purdue.EDU (Gene Spafford)
Newsgroups: comp.windows.x
Subject: Speedups for X11.2 Xsun (CORRECTION)
Message-ID: <4219@medusa.cs.purdue.edu>
Date: 28 May 88 06:35:10 GMT
References: <4211@medusa.cs.purdue.edu>
Reply-To: spaf@cs.purdue.edu (Gene Spafford)
Organization: Department of Computer Science, Purdue University
Lines: 108


Adam de Boor (deboor@nutmeg.berkeley.edu) has pointed out to us that
some braindamaged compilers may not like some of the code we changed in
maskbits.h (the IBM RT was an example he gave).  Since we're using
well-behaved compilers, we'll take his word on that.  He suggested some
restatements of the code to avoid those bugs, and since they have the
same effect as our code without adding extra operations, we'll present
them so our enhancements work for everyone's machines.

Adam also pointed out a small flaw in what we did in putbits (which we
never triggered in our testing, it appears), and a fix for that is
included as well.

Thus, use the following as the patch to maskbits.h rather than
the one we posted yesterday.


*** maskbits.h.orig	Wed May 25 22:38:33 1988
--- maskbits.h	Sat May 28 01:28:45 1988
***************
*** 28,35 ****
--- 28,39 ----
  
  extern int starttab[];
  extern int endtab[];
+ #ifndef PURDUE
  extern int startpartial[];
  extern int endpartial[];
+ #else PURDUE
+ extern unsigned partmasks[32][32];
+ #endif PURDUE
  extern int rmask[32];
  extern int mask[32];
  
***************
*** 206,213 ****
--- 210,222 ----
      else \
  	nlw = (w) >> 5;
  
+ #ifndef PURDUE
  #define maskpartialbits(x, w, mask) \
      mask = startpartial[(x) & 0x1f] & endpartial[((x) + (w)) & 0x1f];
+ #else PURDUE
+ #define maskpartialbits(x, w, mask) \
+     mask = partmasks[(x)&0x1f][(w)&0x1f];
+ #endif PURDUE
  
  #define mask32bits(x, w, startmask, endmask) \
      startmask = starttab[(x)&0x1f]; \
***************
*** 214,219 ****
--- 223,230 ----
      endmask = endtab[((x)+(w)) & 0x1f];
  
  
+ #ifndef PURDUE
+ 
  #define getbits(psrc, x, w, dst) \
  if ( ((x) + (w)) <= 32) \
  { \
***************
*** 244,249 ****
--- 255,293 ----
      *(pdst) = (*(pdst) & endtab[x]) | (SCRRIGHT(src, x) & starttab[x]); \
      *((pdst)+1) = (*((pdst)+1) & starttab[n]) | (SCRLEFT(src, m) & endtab[n]); \
  }
+ 
+ #else PURDUE
+ #define getbits(psrc, x, w, dst) \
+ if ( ((x) + (w)) <= 32) \
+ { \
+     dst = SCRLEFT((unsigned) *(psrc), (x)); \
+ } \
+ else \
+ { \
+     dst = (SCRLEFT((unsigned) *(psrc), (x))) | \
+ 	  (SCRRIGHT((unsigned) *((psrc)+1), 32-(x))); \
+ }
+ 
+ #define putbits(src, x, w, pdst) \
+ { \
+     int n = (x)+(w)-32; \
+     if (n <= 0) \
+     { \
+ 	unsigned tmpmask; \
+ 	maskpartialbits((x), (w), tmpmask); \
+ 	*(pdst) = (*(pdst) & ~tmpmask) | \
+ 		(SCRRIGHT((unsigned) src, x) & tmpmask); \
+     } \
+     else \
+     { \
+ 	unsigned int *ptmp_ = (pdst)+1; \
+ 	int m = 32-(x); \
+ 	*(pdst) = (*(pdst) & endtab[x]) | (SCRRIGHT((unsigned) (src), x)); \
+ 	*ptmp_ = (*ptmp_ & starttab[n]) | \
+ 		(SCRLEFT((unsigned) src, m) & endtab[n]); \
+     } \
+ }
+ #endif PURDUE
  
  #define putbitsrop(src, x, w, pdst, rop) \
  if ( ((x)+(w)) <= 32) \
-- 
Gene Spafford
NSF/Purdue/U of Florida  Software Engineering Research Center,
Dept. of Computer Sciences, Purdue University, W. Lafayette IN 47907-2004
Internet:  spaf@cs.purdue.edu	uucp:	...!{decwrl,gatech,ucbvax}!purdue!spaf