What is faster?

Zap-o

Is it better / faster to use IF statements or a Case statement? I intend on using many statements and for some reason I want to think that case is faster but not sure.

Bobb Fwed

you could put the two types into a program and check the CNT timer at the beginning and the end and figure out the difference between the two.

My guess would also be that the CASE command is faster especially when a significant number of conditions are checked. I would also imagine CASE would use less memory than IFs.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
April, 2008: when I discovered the answers to all my micro-computational-botherations!

jazzed

Spin CASE is very clumsy. It is also limited to 64 cases ... you end up mixing IF and CASE then. If you want to see how it behaves, use BSTC or Homespun for listings and a debugger.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
--Steve

Propeller Tools

• Propalyzer: Propeller PC Logic Analyzer
• BMAD: An on-chip PASM Debugger
• SPUD: Spin Source Level Debugger for Linux/Cygwin

CounterRotatingProps

jazzed said...
Spin CASE is very clumsy. It is also limited to 64 cases ... you end up mixing IF and CASE then.

OH now that's ugly ! ·· The case limit doesn't seem to be documented in the PropMan - did you stumble on that with the 65th case?·


▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔

Kye

The case statement also waste a ton of memory. Really the difference is between a few longs when using ifs.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Nyamekye,

Bobb Fwed

CASE is faster...here is the test code I used:

PUB Main | value, start, time, tmp

  value := 10

  start := cnt
  IF (value == 0)
    tmp~~
  ELSEIF (value == 1)
    tmp~~
  ELSEIF (value == 2)
    tmp~~
  ELSEIF (value == 3)
    tmp~~
  ELSEIF (value == 4)
    tmp~~
  ELSEIF (value == 5)
    tmp~~
  ELSEIF (value == 6)
    tmp~~
  ELSEIF (value == 7)
    tmp~~
  ELSEIF (value == 8)
    tmp~~
  ELSEIF (value == 9)
    tmp~~
  ELSEIF (value == 10)
    tmp~~ 
  time := cnt

  DEBUG.dec(time - start - 368)  ' worst case: 8032 best case: 1200
  DEBUG.tx($0D)    

  start := cnt
  CASE value
    0: tmp~~
    1: tmp~~
    2: tmp~~
    3: tmp~~
    4: tmp~~
    5: tmp~~
    6: tmp~~
    7: tmp~~
    8: tmp~~
    9: tmp~~
    10: tmp~~
  time := cnt

  DEBUG.dec(time - start - 368)  ' worst case: 6224 best case: 1280
  DEBUG.tx($0D)

IF/ELSEIF is worst case: 8032 cycles best case: 1200 cycles
CASE is worst case: 6224 cycles best case: 1280 cycles
And the difference is 8 longs in memory.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
April, 2008: when I discovered the answers to all my micro-computational-botherations!