Is "rev" provided through PropGCC?

Comments

• ersmith Posts: 6,172

  2015-04-18 17:07 edited 2015-04-18 17:07

  SwimDude0614 wrote: »

  The Propeller has a couple pretty cool instructions with no equivalent in C. Specifically, I'm looking for the rev instruction. Is that provided through PropGCC? If not, could it be? I know I can use it via inline assembly, but that's quite verbose for a single instruction.

  x = __builtin_propeller_rev(y, n);
  

  
  Pretty much any Propeller instruction which doesn't have an "obvious" way to write it in C (the lock, wait, etc. instructions, for example) will have a __builtin_propeller_xxx function, where xxx is the PASM opcode (all lower case).
  
  The <propeller.h> include file has nice macro wrappers for many of these, but that's optional.
  
  Eric
• Ariba Posts: 2,693

  2015-04-18 17:09 edited 2015-04-18 17:09

  Have you tried this?

     __builtin_propeller_rev(myVar,0);
  

  I have never used this one, but I think all the Assembler instructions have an equivalent __builtin_ function.
  
  Andy
  
  Edit. Okay Eric was a bit faster - but only a bit..
• DavidZemon Posts: 2,973

  2015-04-18 17:36 edited 2015-04-18 17:36

  ersmith wrote: »

  x = __builtin_propeller_rev(y, n);
  

  
  Pretty much any Propeller instruction which doesn't have an "obvious" way to write it in C (the lock, wait, etc. instructions, for example) will have a __builtin_propeller_xxx function, where xxx is the PASM opcode (all lower case).
  
  The <propeller.h> include file has nice macro wrappers for many of these, but that's optional.
  
  Eric

  
  I thought I saw something like that but couldn't find it. Thanks!
  
  Andy, thanks to you too :P
• DavidZemon Posts: 2,973

  2015-04-19 08:13 edited 2015-04-19 08:13

  Is there a __builtin_propeller_andn? It seems to be missing and x &= ~(y) doesn't compile to andn.
  
  --Edit--
  Or maybe it does, but not when used with CMM?
• Dave Hein Posts: 6,347

  2015-04-19 08:24 edited 2015-04-19 08:24

  No, there is no andn builtin. Here's the complete list.

  propeller/propeller.c: * void __builtin_propeller_clkset(unsigned mode)
  propeller/propeller.c: * int __builtin_propeller_cogid(void)
  propeller/propeller.c: * int __builtin_propeller_coginit(unsigned mode)
  propeller/propeller.c: * void __builtin_propeller_cogstop(int id)
  propeller/propeller.c: * unsigned __builtin_propeller_rev(unsigned x, unsigned n)
  propeller/propeller.c: * unsigned __builtin_propeller_waitcnt(unsigned c, unsigned d)
  propeller/propeller.c: * void __builtin_propeller_waitpeq(unsigned state, unsigned mask)
  propeller/propeller.c: * void __builtin_propeller_waitpne(unsigned state, unsigned mask)
  propeller/propeller.c: * void __builtin_propeller_waitvid(unsigned colors, unsigned pixels)
  propeller/propeller.c: * int __builtin_propeller_locknew(void)
  propeller/propeller.c: * void __builtin_propeller_lockret(int x)
  propeller/propeller.c: * int __builtin_propeller_lockset(int x)
  propeller/propeller.c: * void __builtin_propeller_lockclr(int x)
  
• ersmith Posts: 6,172

  2015-04-19 15:28 edited 2015-04-19 15:28

  SwimDude0614 wrote: »

  Is there a __builtin_propeller_andn? It seems to be missing and x &= ~(y) doesn't compile to andn.

  
  I'm not sure about PropGCC 1.0, but later versions (like alpha v1_9_0) compile:

  unsigned test(unsigned x, unsigned y)
  {
      return x & ~y;
  }
  

  to

  	.text
  	.global	_test
  _test
  	andn	r0, r1
  	lret
  

  in both LMM and CMM mode.
  
  I have seen cases where andn is not used inside loops, though -- unfortunately the loop optimization code sometimes hoists the "~y" part out of the loop, and ends up using more registers as a result.