From: terje.mathisen@nospicedham.tmsw.no   
      
   Rick C. Hodgin wrote:   
   > On 10/14/20 10:00 PM, Melzzzzz wrote:   
   >> On 2020-10-13, Rick C. Hodgin    
   >> wrote:   
   >>> I have two rectangles r1 and r2.  I need to determine if r1 is 1) fully   
   >>> inside, 2) partially inside, or 3) not inside r2.   
   >>> The coordinates are all signed integers ranging from -32768 to +32767.   
   >>   
   >> Too old for this ;)   
   >>   
   >> I think that I solved this problem some 30 years ago :P   
   >   
   > I spent some time searching online for branchless compares to see if I   
   > could find some optimizations that would be useful.   
   >   
   > I remember coming across a page that showed all kinds of optimizations   
   > for adding certain values, subtracting certain values, etc.   
   >   
   > I'm thinking there is a way to take the values and perform only ADD,   
   > SUB, INC, DEC, OR, and XOR to get a result.  If it could be done for a   
   > type of between() function, the rest becomes academic.   
   >   
   You can obviously do a bunch of parallel compares, using SIMD opcodes:   
      
   Each AVX-512 register would hold 32 16-bit ints, so you can splat the   
   ll/ur corners (4 values) of both rectangles (8 total) across up to 8   
   locations:   
      
   --   
   -    
   "almost all programming can be viewed as an exercise in caching"   
      
   --- SoupGate-Win32 v1.05   
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