Re: [cc65] Bank Switching on NES

newsclan(zhblue) a écrit :
> Hi,
> i found this old thread on bank switching,but it makes it quite clean on the theory,but i just need an sample on bank switching.
> http://www.cc65.org/mailarchive/2002-10/1604.html
> 
> i have a lot of const char [] to store in PRGROM.
> i guess it should work like this, but how ?
> 
> 1.use ld65 memory config file to define a memory map (how if i use MMC1),add more bank ROMs in to the config file.
> 2.use #pragma XXXXX ( what exectly should be written?) 
>    to force array value code into certain Segment which defined by the 1st step
> 3.adding code of bank switching before using data in a certain bank.(combined the thread and the MMC1 reference)
> 
> can anyone help? 
> 
> thanks
> zhblue N�����r��y���^�+-��ݙ�������ݢj&����yװ��m��-�)�{.n�+���s�b��^n�r��azf�l===

If you want to do bankswitching on the NES you'd definitely want to 
write the bankswitching routines in assembly even if the rest of the 
programm is in C (as for the interrupt vectors).

#define MMC1Reg1 (*char)0x8000

void writeReg(unsigned char value)
{
	int i;
	*MMC1Reg1 = (char)0x80		//Reset MMC1 register
	for (i == 5; i!=0; --i)
	{
		*MMC1Reg1 = value;	//Write 5 bits
		value = value >> 1;	//shifting right each loop
	}
}

that should work (no guarantee I haven't tried at all), altough it's 
really not a good implementation I belive
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