[balrogsoft]

Hi.
I'm working on my game engine again, and I have performance problems when it runs on stock A600 (whithout acceleration) with Kickstart 2.0. For this system the double buffer is implemented doubling the height of screen and performing a ScrollVPort to the actual frame. When I use this trick, the frame rate drops to the 50%, 25 fps only.

Any idea about why this problem occurs? If I don't use double buffering, I have tried also a basic example blitting a tilemap with vertical scroll from my engine, and there isn't enough time every frame to draw it using amigaos functions, and it only makes a few blittings every frame, it blit the next tile row meanwhile the scroll is running, not a complete row, I must forget something, it's a simple tilemap.

#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#include <exec/execbase.h>
#include <exec/memory.h>  
#include <cybergraphx/cybergraphics.h>
#include <graphics/gfxbase.h>
#include <devices/timer.h>

#include <proto/exec.h>
#include <proto/intuition.h>
#include <proto/graphics.h>
#include <proto/cybergraphics.h>
#include <proto/timer.h>   

#define WIDTH 320
#define HEIGHT 256
#define DEPTH 5

extern struct ExecBase *SysBase;
struct GfxBase *GfxBase;
struct Library *CyberGfxBase= NULL;
struct Library *TimerBase;      /* to get at the time comparison functions */
static struct IORequest timereq;

UWORD __chip EmptyPointer[] = {0, 0, 0, 0};

ULONG timer(void)
{
  static struct timeval tt;
  struct timeval a, b;

  GetSysTime(&a);
  b = a;
  SubTime(&b, &tt);
  tt = a;

  return b.tv_secs*1000 + b.tv_micro/1000;
}

int main(void)
{
    struct Screen *screen;
    struct Window *window;
    struct DimensionInfo dimsinfo;

        ULONG mtimer = 0;
        int elapsed=0;
        WORD fps=0;
        WORD fps_val=0;
   
    LONG oscan_height,frame=0,frameOffset=0;
        UBYTE numstr[16];
                        
    OpenDevice("timer.device", 0, &timereq, 0);
        TimerBase = timereq.io_Device;
    GfxBase = (struct GfxBase *) OpenLibrary( "graphics.library", 0 );
                    
    if (CyberGfxBase = OpenLibrary("cybergraphics.library",0))
    {
        CloseLibrary(CyberGfxBase);
    }
    
        
    GetDisplayInfoData(FindDisplayInfo(LORES_KEY), (UBYTE *)&dimsinfo,
                               sizeof(struct DimensionInfo), DTAG_DIMS,
                               NULL);
                               
    oscan_height = dimsinfo.MaxOScan.MaxY - dimsinfo.MaxOScan.MinY + 1;

    screen = OpenScreenTags(NULL,
                           SA_DisplayID, PAL_MONITOR_ID|LORES_KEY,
                           SA_Width,     WIDTH,
                           SA_Height,    oscan_height<<1,
                           SA_Depth,     DEPTH, 
                           SA_Type,      CUSTOMSCREEN,
                           SA_Quiet,     TRUE,
                           SA_Draggable, FALSE,
                           SA_Exclusive, TRUE,
                           SA_Interleaved, TRUE,
                           SA_AutoScroll, FALSE,
                           TAG_DONE);
        
    window = OpenWindowTags(NULL,
                            WA_CustomScreen, screen,
                            WA_Flags, WFLG_BORDERLESS | WFLG_ACTIVATE,
                            WA_IDCMP, 0,
                            TAG_DONE);
        
       
    SetPointer(window, EmptyPointer, 1L, 1L, 0L, 0L);

        elapsed = timer();
    while((*(UBYTE *)0xBFE001) & 0x40)
    {  
        frame ^= 1;
        frameOffset = frame*oscan_height;                 // <--- Comment this line to disable double buffer
                
                fps++;
                        
                elapsed = timer();
                
                mtimer+=elapsed;
                if (mtimer>1000)
                {
                        fps_val = fps;
                        fps = 0;
                        mtimer=mtimer-1000;
                }
                
                sprintf(numstr, "%d fps", fps_val);
                                        
                SetAPen(&screen->RastPort, 31);
                Move(&screen->RastPort, 10, 10+frameOffset);
                Text(&screen->RastPort, numstr, strlen(numstr));
                
        screen->ViewPort.RasInfo->RyOffset = frameOffset; //  <--- Comment this line to disable double buffer
        ScrollVPort(&screen->ViewPort);                   //  <--- Comment this line to disable double buffer
    
        WaitTOF();
    }; 
    
        CloseWindow(window);
    CloseScreen(screen);

    CloseDevice(&timereq);
        
    if(GfxBase)
        CloseLibrary((struct Library *)GfxBase);
        
    return 0;
}