cc65: Graphics 8 pixel plotters...

[sanny]

You mean this (unsigned char *) makes the difference?

 

Use cc65 to create assembly output and show the different invocations of memset.

 

regards,

chris

[TGB1718]

I just tried a compile using both with and without a cast to memset()  and the output is identical.

Must have been something else causing the problem.

 

000083r 1  AD rr rr         lda     L0030
000086r 1  85 rr            sta     ptr1
000088r 1  A0 4F            ldy     #$4F
00008Ar 1  A9 AA            lda     #$AA
00008Cr 1  91 rr        L0035:    sta     (ptr1),y
00008Er 1  88               dey
00008Fr 1  10 FB            bpl     L0035
 

[stepho]

I had a quick look at your code and couldn't find PST .

But I did find your definition of SAVMSC .

#define SAVMSC *((word *) 0x0058)

 

I guess you wanted to do something like SAVMSC=0xff at some point.
The leftmost * in the define makes SAVMSC equivalent to an integer variable (not a pointer), so this works.
But it doesn't work for memset(), which expects a pointer.

#define SAVMSC *((word *) 0x0058)
SAVMSC = 0xff; // saves 0xff to SAVMSC, ie *(0x58) = 0xff
memset( SAVMSC, 0, 1); // writes 0 to whatever is at address 0xff, ie reads SAVMSC and uses that as the address to write 0xff to
memset( (byte*)SAVMSC, 0, 1); // writes 0 to whatever is at address 0xff
 

Instead try either of the following techniques:

#define SAVMSC *((word *) 0x0058)
SAVMSC = 0xff; // saves 0xff to SAVMSC, ie *(0x58) = 0xff
memset( &SAVMSC, 0, 1); // writes 0 to address 0x58
 

Or

#define SAVMSC ((word *) 0x0058)
*SAVMSC = 0xff; // saves 0xff to SAVMSC, ie *(0x58) = 0xff
memset( SAVMSC, 0, 1); // writes 0 address 0x58
 

[Wrathchild]

I would really recommend switching to use stdint.h which defines:

typedef signed char         int8_t;
typedef int                 int16_t;
typedef long                int32_t;
typedef unsigned char       uint8_t;
typedef unsigned            uint16_t;
typedef unsigned long       uint32_t;

 

[atarixle]

21 hours ago, TGB1718 said:

You shouldn't need the cast as long as PST has been defined as char *PST

Also all pointers are unsigned, they are purely 16 bit addresses so "unsigned" is also not needed.

I think that definition may have somehow confused the compiler

That is a quite good idea, but PST is #defined as PEEKW(88). I guess I will have to create a definition that works without the use of the PEEK statements.

[TGB1718]

Still can still use PEEKW, just change the code to something like this.

 

int *PST;

 

PST=(int *)PEEKW(88);

 

or even

 

char *PST;

 

PST=(char *)PEEKW(88)

 

a char pointer is still 2 bytes, so will act just the same as the int pointer, you can still use POKEW to a char pointer

or even something like

char *PST;

PST=(char *)PEEKW(88);

*PST=0xaa55; // still pokes 2 bytes

[ClausB]

On 5/23/2022 at 9:57 PM, damosan said:

the fastest I've managed (~332 pixels / jiffy) on an NTSC machine

FS1 manages 400-500 pixels per frame (1/60 sec - I think that's what you're calling a jiffy).

[atarixle]

PST is not an assignment, it's a definition. So or so it results in a casted thing that somehow breaks in cc65-master.