/*
 * Testing inline assembler with HI-TECH C under CP/M
 * Version for PC CP/M emulator w/o OUT instructions
 */

#include <stdio.h>

	void testNegation();
	void digitalWrite(char dataPin, char state);
	
	void fnctpar(unsigned int);
	void regvar1();
	void regvar2();
	
	unsigned char portData;
	
#ifndef false
#define false 0
#endif
#ifndef true
#define true 1
#endif

#ifndef LOW
#define LOW 0
#endif
#ifndef HIGH
#define HIGH 1
#endif


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

	
	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. 
		
		L.V.: Note 2 - register hint for pointer works, IY is used for it (max one). See regvar3() in HELLOEMU.AS
	*/

	printf("Getting register-variable to register pair - OPTIMALIZED\n");
	regvar1();
	printf("--------------------------------------\n");
	printf("Getting register-variable to register pair - NOT OPTIMALIZED\n");
	regvar2();
	printf("--------------------------------------\n");
	regvar3();
	
	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 = 0;
	
#asm
		PUSH AF
		PUSH HL
		
		PUSH IY
		POP HL					; HL <= IY
		
		/* 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 (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 */
}

regvar3()
{
		char ch1; 
		register char *p_ch1;
		
		char ch2; 
		register char *p_ch2;
	
		ch1 = ' ';
		p_ch1 = &ch1;  			/* Store address of 'ch1' in pointer variable, register IY is used */
		*p_ch1 = 'x';			/* LD (IY+0), 120 */
		
		ch2 = ' ';
		p_ch2 = &ch2;  			/* Store address of 'ch2' in pointer variable, only one pointer may be optimalized by 'register' keyword so IY isn't used */
		*p_ch2 = 'y';			/* LD (IY+0), 120 */
		
		printf("ch1: %c, ch2: %c\n", ch1, ch2);
}

/* 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'
		
		/* Local variables can be accessed by IX-displacement */
		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 */
}