programming in c using cpcrslib and z88dk

[arnoldemu]

I wanted to define a fixed length string, and then set the last char in the string so that I could load different backgrounds.

This is the magic:

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static char *String[] = "BANGEL69.BK0";

.
.
.

Filename(sizeof(Filename)-2] = 0x030+Index;


The first defines a string array.

sizeof() returns length of string including null terminator (\0 or 0 char).
So we have to subtract 2 to get to last char in string.
Then we can set it.

[norecess]

I hope you don't have more than 10 images to load
In the end, I think it's safer+easier to use a custom bigfile-system : many packed files stored in a single file, with an index table to retrieve them - ... so in the end, you would have  Unpack( FileID, 0xC000 ) (0xc000 being any char ptr).

[arnoldemu]

If you use:

const unsigned short Value=13;

and then reference it in your code, the z88dk compiler actually generates a word value:

Value:
defw 13

and then in the code does this to use it:

ld hl,(_Value)

So If you want a constant value, use #define e.g.

#define Value 13

In addition, if your #define results in a constant, ensure you use enough brackets. e.g.

#define tile_width 8
#define tile_height 16
#define tile_size (tile_width>>1)*tile_height

should be written as:

#define tile_width 8
  #define tile_height 16
  #define tile_size ((tile_width>>1)*tile_height)

If you don't do this, and you use tile_size in arithmetic, then the compiler could end up generated non-optimised code.
With the extra brackets in there you force the compiler to evaluate this, realise it is constant and use more optimised code.

[norecess]

Good tip. 

[arnoldemu]

Good tip. 

I need all the help I can to squeeze Blue Angel 69 into ram now that I've fixed the AI


BTW, I haven't forgotten about that header file I was going to make for you. Been really busy recently.

[arnoldemu]

If you have code like this:

Code Select Expand


If (Tile<0)
{
TileGfx = 23;
}
else
{
TileGfx = 22;
}


Writing it as this will save some bytes:

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TileGfx = (Tile<0) ? 23 : 22;


[arnoldemu]

If you have code like this:

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Player1Type = HUMAN;
Player2Type = HUMAN;


If you write it like this:

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Player1Type = Player2Type = HUMAN;


This will also save bytes.

The generated code for this first is like this:

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ld hl,HUMAN
ld (Player1Type),hl
ld hl,HUMAN
ld (Player2Type),hl


And for the second:

Code Select Expand


ld hl,HUMAN
ld (Player1Type),hl
ld (Player2Type),hl


EDIT: Note this doesn't apply to arrays. So Array[0] = Array[1] = 3; will not generate efficient code as you think

[norecess]

Which compiler are you using?

[arnoldemu]

Which compiler are you using?

all of this applies to z88dk version 1.9

when I've finished this project I will look at other compilers

[norecess]

Yeah, I have been personally happy to switch from z88dk to SDCC. I globally found it less hacky and much cleaner. The only thing that really suck with SDCC is its ASM syntax.

[AMSDOS]

arnoldemu wrote:

all of this applies to z88dk version 1.9

when I've finished this project I will look at other compilers

Compilers are wonderful, I just hope people aren't writing them for the sake of writing them though! 

[arnoldemu]

arnoldemu wrote:

all of this applies to z88dk version 1.9

when I've finished this project I will look at other compilers

Compilers are wonderful, I just hope people aren't writing them for the sake of writing them though! 

I don't think so. There are 2 major compilers running on pc that will generate z80 code.
sdcc and z88dk, both have been around for a while and both have fairly good libraries.

The project is now finished!
Next project will start in a couple of weeks and this time I will be using asm.

[AMSDOS]

arnoldemu wrote:

I don't think so. There are 2 major compilers running on pc that will generate z80 code.
sdcc and z88dk, both have been around for a while and both have fairly good libraries.

Yes it seems that since I made those last remarks about people just making compilers for the sake of it, that indeed people in the communties are using them to good extent. There is perhaps also arguments now that even BASIC could be used as an alternative given a compiler is available which supports Locomotive BASIC & Sprites Alive. Other languages or game kits have emerged, I don't think Pandora was on NVG a couple of years ago ( ??). Guess that's crying out for a manual, though Sprites Alive probably has more advantages and an edge over Pandora.

The project is now finished!
Next project will start in a couple of weeks and this time I will be using asm.

There's always one language the CPC is best at though! 

[TFM]

The project is now finished!
Next project will start in a couple of weeks and this time I will be using asm.

There's always one language the CPC is best at though! 

Indeed! 

[demoniak]

Norecess: the links to your projets seems to be broken...