new version

[Chiptunes-pms150c.git] / bsv.c

#include <stdio.h>
#include "fakeasm.h"
typedef unsigned char u8;

u8 i0, i1, i2; //MEM
u8 n; //MEM
u8 sample; //MEM
u8 tmp_1; //MEM
u8 acc; //ACC

u8 notes[] = {
	0x84, 0x9d, 0xb0, 0x69, 0x9d, 0x84, 0x69, 0x58,
	0x75, 0x8c, 0xb0, 0x69, 0x8c, 0x75, 0x69, 0x58
};

u8 mod3hi, mod3lo;
void mod3(void) {
	acc = (mod3hi<<8|mod3lo) % 3;
}

void g(void){
	u8 notes_ix = acc & 0x7;
	if(3&i2)
		notes_ix += 8;
	u8 result = ((i1<<8|i0)*notes[notes_ix])>>8;  // keep hi byte
	acc = result;
}
void main(void){
	CLEAR	(i0)
	CLEAR	(i1)
	CLEAR	(i2)
	for(;;) {
		MOV	(acc, i2)// "mov mem,mem"
		MOV	(n, acc)// does not exist
		SL	(n)
		SL	(n)
		MOV	(acc, i1)
		SWAP	(acc)
		AND	(acc, 0xf)
		SR	(acc)
		SR	(acc)
		OR	(n, acc)

		MOV	(acc, n)
		CALL	(g)
		SWAP	(acc)
		AND	(acc, 0x1)
		MOV	(sample, acc)

		MOV	(acc, i2)
		SL	(acc)
		SL	(acc)
		SL	(acc)
		MOV	(tmp_1, acc) // fresh tmp_1:
		MOV	(acc, i1)
		SWAP	(acc)
		AND	(acc, 0xf)
		SR	(acc)
		OR	(acc, tmp_1) // tmp_1 done.
		XOR	(acc, n)
		CALL	(g)
		SR	(acc)
		AND	(acc, i2)
		SR	(acc)
		AND	(acc, 3)
		ADD	(sample, acc)

		mod3hi = i2>>3;
		mod3lo = i2<<5|i1>>3;
		mod3();
		ADD	(acc, n)
		CALL	(g)
		SR	(acc)
		SR	(acc)
		MOV	(tmp_1, acc) // acc saved in tmp_1; fresh acc
		MOV	(acc, i2)
		// shift-divide by six
		// note: i2 is max 0x78; so acc will <= 20. (breaks vor values >=128)
                SR	(acc)
		ADD	(acc, i2)
		SR	(acc)
                SR	(acc)
		ADD	(acc, i2)
		SR	(acc)
                SR	(acc)
		ADD	(acc, i2)
		SR	(acc)
		SR	(acc)
		SR	(acc)
		// end divide by six
		AND	(acc, tmp_1) // acc restored from tmp_1
		AND	(acc, 3)
		ADD	(sample, acc)

		MOV	(acc, n)
		ADD	(acc, 8)
		{ u8 tmp3 = ((i2<<6|i1>>2)&0x1fff)%3;
		  SUB	(acc, tmp3)
		} // tmp3
		CALL	(g)
		SR	(acc)
		MOV	(tmp_1, acc) // acc saved in tmp_1; fresh acc
		MOV	(acc, i2)
		// shift-divide by ten
		// note: i2 is max 0x78; so acc will <= 12.
                INC	(i2)
                SR	(acc)
                ADD	(acc, i2)
                SR	(acc)
                SR	(acc)
                SR	(acc)
                ADD	(acc, i2)
                SR	(acc)
                ADD	(acc, i2)
                SWAP	(acc)
                DEC	(i2)
		// end divide by ten
		AND	(acc, tmp_1) // acc restored from tmp_1
		AND	(acc, 3)
		ADD	(sample, acc)

		MOV	(acc, sample)
		SWAP	(acc)
		putchar(acc);

		INC	(i0)
		i1 += !i0; // ADDC i1
		i2 += !i1 && !i0; // ADDC i2
	}
}