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how to speed up

lee Rhett

Hi All

Consult a while, has any tips can speed the judgment of"Switch case" in keil c??

Seem to make the common use parameter putting the front to judge first ??

For examples,if c equal one more then equal two

so we can write down like this

   switch(c)
  {
   case 1:
      break;
   case 2:
      break;
  }

an we don't use this type

   switch(c)
  {
   case 2
      break;
   case 1
      break;
  }

Is any tips like this can use in "switch case" in
keil c??

Sorry for my poor english^^"""

Thanks

Parents
  • 0 in reply to Drew Davis

    Thanks all

    I just want to know

    1 how is ccase realy do??

    2 how can we write the correct code to help complier to output great code

    3 how to write my own if-then-else chain or others ?? is any example code??

    for now,it seem look like the parameter of switch

    is much better in order and closed

    CODE1

    #define AA 0
#define BB 1
#define CC 2
        ~
#define ZZ 26

switch(c)
{

  case AA:
   break;
     ~
  case ZZ:
   break;
}

    CODE2

    #define AA 0
#define BB 10
#define CC 20
        ~
#define ZZ 255

switch(c)
{

  case DD:
   break;
     ~
  case GG:
   break;

  case MM:
   break;
}

    if the value of c is form AA to ZZ ,The code1 speed is faster then the code2 in optimizer level 7

    thanks a again

Reply
  • 0 in reply to Drew Davis

    Thanks all

    I just want to know

    1 how is ccase realy do??

    2 how can we write the correct code to help complier to output great code

    3 how to write my own if-then-else chain or others ?? is any example code??

    for now,it seem look like the parameter of switch

    is much better in order and closed

    CODE1

    #define AA 0
#define BB 1
#define CC 2
        ~
#define ZZ 26

switch(c)
{

  case AA:
   break;
     ~
  case ZZ:
   break;
}

    CODE2

    #define AA 0
#define BB 10
#define CC 20
        ~
#define ZZ 255

switch(c)
{

  case DD:
   break;
     ~
  case GG:
   break;

  case MM:
   break;
}

    if the value of c is form AA to ZZ ,The code1 speed is faster then the code2 in optimizer level 7

    thanks a again

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