/*
 * Testing inline assembler with HI-TECH C under CP/M
 */

#include <stdio.h>

	void fnctpar(unsigned int);
	void regvar1();
	void regvar2();
	void delay(long);


/* Entry point to program */
int main()
{
	unsigned int i;
	char c;
	
	printf("Hello world !\n");

	/* Set SC103 - Z80 PIO's to output mode */
#asm
		PUSH AF
		LD A, 0FH
		OUT (6AH), A
		OUT (6BH), A
		OUT (6EH), A
		OUT (6FH), A
		POP AF
#endasm

	printf("======================================\n");
	printf("Getting function parameter to register\n");
	fnctpar(170);
	printf("--------------------------------------\n");
	printf("Press Enter to continue...");
	scanf("%c", &c, 1);

	fnctpar(85);
	printf("======================================\n");
	printf("Press Enter to continue...");
	scanf("%c", &c, 1);

	fnctpar(3855);
	printf("--------------------------------------\n");
	printf("Press Enter to continue...");
	scanf("%c", &c, 1);
	
	printf("======================================\n");

	/* 
		This page says: www.vcfed.org/forum/archive/index.php/t-50530.html
		If there is a register variable (there is at most one) it's in register IY 
		
		L.V.: Note this is NOT TRUE, variable declared as 'register' is accessible via IX-displacement as other local variables !
		'register' it is just a hint to the compiler. It is up to the latter to satisfy your desire or not. 
	*/

	printf("Getting register-variable to register pair - OPTIMALIZED\n");
	regvar1();
	printf("--------------------------------------\n");
	printf("Getting register-variable to register pair - NOT OPTIMALIZED\n");
	regvar2();
	printf("Press Enter to continue...");
	scanf("%c", &c, 1);
		
	printf("======================================\n");
	printf("Getting local variable to register pair\n");
	for (i = 0; i < 65535; i++)
	{
#asm
		PUSH AF
		PUSH HL
		
		/* Local variables can be accessed by IX-displacement */
		LD H, (IX-1) 			; Pick up the high-byte of local 'i'
		LD L, (IX-2) 			; Pick up the low-byte of local 'i'
		
		LD A, L
		OUT (00H), A
		OUT (068H), A
		CPL
		OUT (06CH), A
		
		LD A, H
		OUT (069H), A
		CPL
		OUT (06DH), A
		
		POP HL
		POP AF
#endasm

		delay(500l);

		if (i % 256 == 0)
			printf("\ni: %u\n", i);
		else
			printf(".");
	}
	
	printf("\n");
	return 0;
}

/* Getting register-variable to register pair HL */
/* Expect, that compiler optimalized storing 'register unsigned int ri' to IY */
void regvar1()
{
	register unsigned int ri = 3855; /* 0000111100001111 */
	unsigned int iy_copy;

#asm
		PUSH AF
		PUSH HL
		
		DEFB 0FDH, 7DH		; LD A, IYL (Undocumented)
		OUT (00H), A
		OUT (68H), A
		OUT (6CH), A
		LD L, A
		DEFB 0FDH, 7CH		; LD A, IYH (Undocumented)
		OUT (69H), A
		OUT (6DH), A
		LD H, A

		/* Local variables can be accessed by IX-displacement */
		/* Because we expect that 'ri' is in IY, iy_copy is at IX-1, IX-2 */
		LD (IX-1), H 		; Put the high-byte to local 'iy_copy'
		LD (IX-2), L 		; Put the low-byte to local 'iy_copy'
		
		POP HL
		POP AF
#endasm
	
	/* This comparsion fails */
	printf("ri: %d, iy_copy: %d\n", ri, iy_copy); /* Assure that ri and iy_copy have the same value */
	printf("ri: %4.4x, iy_copy: %4.4x\n", ri, iy_copy); /* Assure that ri and iy_copy have the same value */
}

/* Getting register-variable to register pair HL */
/* Expect, that compiler DO-NOT optimalized storing 'register unsigned int ri' to IY */
void regvar2()
{
	register unsigned int ri = 3855; /* 0000111100001111 */
	unsigned int li = 0;

#asm
		PUSH AF
		PUSH HL
		
		/* Local variables can be accessed by IX-displacement */
		LD H, (IX-1) 		; Pick up the high-byte of reg. local 'ri'
		LD L, (IX-2) 		; Pick up the low-byte of reg. local 'ri'
		LD A, L
		OUT (00H), A
		OUT (68H), A
		OUT (6CH), A
		LD A, H
		OUT (69H), A
		OUT (6DH), A
		
		LD (IX-3), H 		; Put the high-byte to local 'li'
		LD (IX-4), L 		; Put the low-byte to local 'li'
		
		POP HL
		POP AF
#endasm
	
	/* This comparsion success */
	printf("ri: %d, li: %d\n", ri, li); /* Assure that ri and li have the same value */
	printf("ri: %4.4x, li: %4.4x\n", ri, li); /* Assure that ri and li have the same value */
}

/* Getting function parameter to register */
void fnctpar(unsigned int fi)
{
	unsigned int li = 0;

#asm
		PUSH AF
		PUSH HL

		/* Function parameters can be accessed by IX+displacement */
		/* The first argument is located at (IX+6) */
		LD H, (IX+7) 		; Pick up the high-byte of parameter 'fi'
		LD L, (IX+6) 		; Pick up the low-byte of parameter 'fi'
		
		LD A, L
		OUT (00H), A
		OUT (68H), A
		OUT (6CH), A
		LD A, H
		OUT (69H), A
		OUT (6DH), A
		
		LD (IX-1), H 		; Put the high-byte to local 'li'
		LD (IX-2), L 		; Put the low-byte to local 'li'

		POP HL
		POP AF
#endasm

	printf("fi: %d, li: %d\n", fi, li); /* Assure that fi and li have the same value */
	printf("fi: %4.4x, li: %4.4x\n", fi, li); /* Assure that fi and li have the same value */
}

void delay(long duration)
{
	long i;
	for (i = 0; i < duration; i++)
	{	
		;
#asm			
		NOP
#endasm	
	}
}