Implementing switch case | ImHex 🔎 | Page 1

lethal swift Jul 23, 2024, 2:23 AM

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Sorry for the beginner question, I’m pretty new here valcurious . The compiler is giving me 4 different syntax errors that all seem nonsensical, how would i correctly do this without several nested if else statements?

enum ImageFormats : u32 {
  I4 = 0,
  I8 = 1,
  IA4 = 2,
  IA8 = 3,
  RGB565 = 4,
  RGB5A3 = 5,
  RGBA8 = 6,
  C4 = 8,
  C8 = 9,
  C14X2 = 10,
  CMPR = 14,
};

fn calculateImageSizeBytes(ImageFormats format, u16 width, u16 height) {
    u16 blockWidth;
    u16 blockHeight;
    u32 bytesPerBlock;

    switch (format) {
        case I4:
        case C4:
        case CMPR:
            blockWidth = 8;
            blockHeight = 8;
            bytesPerBlock = 32;
            break;

        case I8:
        case IA4:
        case C8:
            blockWidth = 8;
            blockHeight = 4;
            bytesPerBlock = 32;
            break;

        case IA8:
        case RGB565:
        case RGB5A3:
        case C14X2:
            blockWidth = 4;
            blockHeight = 4;
            bytesPerBlock = 32;
            break;

        case RGBA8:
            blockWidth = 4;
            blockHeight = 4;
            bytesPerBlock = 64;
            break;
    
    }

   u32 total_blocks_width = width / blockWidth;
      if (width % blockWidth > 0) {
         total_blocks_width += 1;
      }
         
   u32 total_blocks_height = height / blockHeight;
      if (height % blockHeight > 0) {
          total_blocks_height += 1;
      }    
   u32 totalBytes = total_blocks_width * total_blocks_height * bytesPerBlock;

    return totalBytes;
    
}

verbal whale Jul 23, 2024, 2:29 AM

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Pattern language doesnt have a switch statement and implements the superior rustlike match statement instead

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Read about its syntax and use in the docs at https://docs.werwolv.net/pattern-language/core-language/control-flow

Control flow | Pattern Language

lethal swift Jul 23, 2024, 2:54 AM

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is there a better way to do this?

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I must be doing something wrong. it states that blockWidth is 0 and thus resulting in a divide by zero error. Trying to debug with pragma debug causes the evaluation to hang and a memory leak opens

verbal whale Jul 23, 2024, 3:09 AM

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pragma debug is not for debugging. what shoulf blockWidth be?

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to debug place a breakpoint and run as normally

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you are not using blockWidth to divide in the code shown.

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A way I would clean that and make it faster is b y defining constants using const

lethal swift Jul 23, 2024, 3:13 AM

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_ _

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it seems like blockwidth was assigned a value 0

verbal whale Jul 23, 2024, 3:15 AM

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try passing it as a reference using ref

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like this ref auto width

lethal swift Jul 23, 2024, 3:21 AM

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results in either
error: Expected value, got Keyword (ref).
or

E: error: Invalid function statement.
E:   -->   in <Source Code>:45:32
E: 45 |  (ImageFormats::RGBA8): ref auto blockWidth =

verbal whale Jul 23, 2024, 3:22 AM

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no, i meant in the function parameter definition

lethal swift Jul 23, 2024, 3:23 AM

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blockWidth isnt passed to the function though?

verbal whale Jul 23, 2024, 3:23 AM

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i thought the problem was with width

lethal swift Jul 23, 2024, 3:23 AM

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lethal swift _ _

no, blockWidth is 0

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so an error is thrown because it tries to divide 32 by 0. a value wasnt assigned to blockWidth by the match statement

verbal whale Jul 23, 2024, 3:25 AM

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you dont jave a default clause. Are you sure it is being assigned a value?

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you dont need one case per variable

lethal swift Jul 23, 2024, 3:26 AM

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format is correctly assigned a value,
in this case, CMPR

verbal whale Jul 23, 2024, 3:27 AM

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the thing is the way you hhave it it may not execute the assignent

lethal swift Jul 23, 2024, 3:28 AM

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verbal whale you dont need one case per variable

what's the correct syntax to use here?

verbal whale Jul 23, 2024, 3:28 AM

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the syntax for match is

match (variavle) {
  (case 1) : {
      statements here
  } 
...
}

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issimilar to how switch works

lethal swift Jul 23, 2024, 3:30 AM

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ah, the documentation's examples didn't use case

verbal whale Jul 23, 2024, 3:31 AM

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maybe it is not using {} if only one statement is needed but the case must always exist

lethal swift Jul 23, 2024, 3:35 AM

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now it states my enums arent declared anymore glace_wasted

    match (format) {
        (case ImageFormats::I4/ImageFormats::C4/ImageFormats::CMPR): {
        blockWidth = 8;
        blockHeight = 8;
        bytesPerBlock = 32;
        };

        (case ImageFormats::I8/ImageFormats::IA4/ImageFormats::C8):  {
        blockWidth = 8;
        blockHeight = 4;
        bytesPerBlock = 32;
        };

        (case ImageFormats::IA8/ImageFormats::RGB565/ImageFormats::RGB5A3/ImageFormats::C14X2): { 
        blockWidth = 4;
        blockHeight = 4;
        bytesPerBlock = 32;
        };

        (case ImageFormats::RGBA8): {
        blockWidth = 4;
        blockHeight = 4;
        bytesPerBlock = 64;
        }
    }

verbal whale Jul 23, 2024, 3:35 AM

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no, no case sorry

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that was just a description of what goes inside the parenthesis

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you had the case syntax correctly, just too maky of them

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many

lethal swift Jul 23, 2024, 3:37 AM

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back to dividing by zero, i have no clue why blockWidth isnt being assigned a value

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does it have something to do with scope?

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none of them are being assigned, blockWidth is just the first one it tries

verbal whale Jul 23, 2024, 3:39 AM

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use std::print("{}",blockWidth); after being assigned and before it is used.

lethal swift Jul 23, 2024, 3:40 AM

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so it looks like the code path isn't being taken. the print statement isn't met and neither is my breakpoint

verbal whale Jul 23, 2024, 3:41 AM

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what value does format have?

lethal swift Jul 23, 2024, 3:41 AM

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in this case, 14

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which is a valid entry in the enum

enum ImageFormats : u32 {
  I4 = 0,
  I8 = 1,
  IA4 = 2,
  IA8 = 3,
  RGB565 = 4,
  RGB5A3 = 5,
  RGBA8 = 6,
  C4 = 8,
  C8 = 9,
  C14X2 = 10,
  CMPR = 14,
};

verbal whale Jul 23, 2024, 3:42 AM

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but you are checking for a value like

ImageFormats::I8/ImageFormats::IA4/ImageFormats::C8

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which is dividing the constants

lethal swift Jul 23, 2024, 3:43 AM

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okay it works if i place the enum entry in its own satement:

        (ImageFormats::CMPR): {
        blockWidth = 8;
        blockHeight = 8;
        bytesPerBlock = 32;
        }

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something must be wrong with putting multiple values together with /

verbal whale Jul 23, 2024, 3:44 AM

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ypu problably mean to use | for or and not / for divide

lethal swift Jul 23, 2024, 3:45 AM

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oh.. this is a pipe...

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its italic so it looks like a forwardslash

verbal whale Jul 23, 2024, 3:46 AM

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ah, I remember seeing that, apparently it is a font issue and there is nothing we can do

lethal swift Jul 23, 2024, 3:47 AM

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thanks for your help, i'm sorry for how long this took woweeThump

verbal whale Jul 23, 2024, 3:47 AM

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maybe remove that text and add a picture would help

#Implementing switch case