[hatari-devel] Strange CPU cycles

Laurent Sallafranque laurent.sallafranque at free.fr
Tue Feb 23 13:01:42 CET 2010


Hello,

I've added the following spy in the code :

/**
 * Run DSP for certain cycles
 */
void DSP_Run(int nHostCycles)
{
#if ENABLE_DSP_EMU
    /* Cycles emulation is just a rough approximation by now.
     * (to be tuned ...) */
    int i = nHostCycles * 2 + 2;
    int dsp_cycle = 0;

    if (i > 50)
        fprintf(stderr, "%d i\n", i);

...

I've started a demo. From Falcon boot to demo running ,I've got many 
68030 instructions that are > 50 cycles :
...
86 i
86 i
258 i
82 i
54 i
274 i
82 i
54 i
262 i
82 i
54 i
270 i
82 i
54 i
270 i
...


This is just a small copy of what I get in real.

How is it possible that a 68030 takes 258 cycles ?
As DSP code and crossbar code are relative to CPU cycles, it looks 
strange for me.


Regards,

Laurent



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