Set / Clear Flags

Comments

• Phil Pilgrim (PhiPi) Posts: 23,514

  2014-04-02 08:39 edited 2014-04-02 08:39

  Here's the thread:
  
  http://forums.parallax.com/showthread.php/108002
  
  -Phil
• JonnyMac Posts: 9,566

  2014-04-02 08:40 edited 2014-04-02 08:40

  Thanks, Phil!
• lonesock Posts: 917

  2014-04-02 09:08 edited 2014-04-02 09:08

  Using the instructions themselves as data always struck me as very clever, but since I have a hard time parsing what the code is supposed to do I tend to use an automatically-zeroed special register, like (untested...from memory):

  { C=0 Z=0 } cmpsub outb, #1 wc,wz
    { C=1 Z=1 } cmpsub outb, #0 wc,wz
    { C=0 Z=1 } cmp  outb, #0 wc,wz
    { C=1 Z=0 } cmp  outb, #1 wc,wz
  

  Jonathan
• HydraHacker Posts: 80

  2014-04-10 15:20 edited 2014-04-10 15:20

  Hi Guys,
  I believe that this code below will save both the Z & C flags and restore them.
  
  save flags
  
  muxnz ZC, #2
  muxc ZC, #1
  
  restore
  
  sar ZC, #1 wz, wc
  
  HydraHacker
• Phil Pilgrim (PhiPi) Posts: 23,514

  2014-04-10 16:19 edited 2014-04-10 16:19

  HydraHacker wrote:

  save flags
  
  muxnz ZC, #2
  muxc ZC, #1
  
  restore
  
  sar ZC, #1

  
  Very slick, indeed (but don't forget to wc,wz in the sar).
• HydraHacker Posts: 80

  2014-04-10 16:30 edited 2014-04-10 16:30

  Thanks Phil,
  
  I added the WZ and WC effects, I had it wrote down on my paper but forgot to include it.
  
  HydraHacker