#include <pic18fregs.h>
#include <stdio.h> 
#include <math.h> 
#include <my_serial.h> 

extern char stack; 
extern char stack_end;

#pragma stack 0x100 256

void _reset (void) __naked __interrupt 0;
void _startup (void) __naked;

static char counter_1hz;	       
static volatile short counter_10hz;	       
static volatile unsigned int softintrs;
#define INT_10HZ	 0x0001
#define INT_AD		 0x0002
#define INT_DOAD	 0x0004

#define TIMER0_5MS 192 /* 48 without PLL */

#define TIMER2_10HZ 1000

#define CLRWDT __asm__("clrwdt")      
#define SLEEP __asm__("sleep")      

static char ad_channel;
static long ad_i_result;
static long ad_v_result;

#define PRINTHEX(v) \
	{ \
		unsigned char c = (v); \
		if (c < 10) { \
			putchar('0' + c); \
		} else { \
			putchar(('a' - 10) + c ); \
		} \
	}

void
main(void) __naked
{
	unsigned char c;
	softintrs = 0;
	counter_1hz = 10;

	ANCON0 = 0xf0; /* an0-an3 analog, an4-an7 digital */
	ANCON1 = 0x3f; /* an8-12 digital */

	TRISCbits.TRISC1 = 0;
	TRISCbits.TRISC2 = 0;
	PORTCbits.RC1 = 0;
	PORTCbits.RC2 = 0;


	/* switch PLL on */
	OSCTUNEbits.PLLEN = 1;

	/* configure sleep mode: PRI_IDLE */
	OSCCONbits.SCS = 0;
	OSCCONbits.IDLEN = 1;
	/* everything is low priority by default */
	IPR1 = 0;
	IPR2 = 0;
	IPR3 = 0;
	IPR4 = 0;
	IPR5 = 0;
	INTCON = 0;
	INTCON2 = 0;
	INTCON3 = 0;
	INTCON2bits.RBPU = 1;

	RCONbits.IPEN=1; /* enable interrupt priority */

	/* configure timer0 as free-running counter at 46.875Khz */   
	T0CON = 0x07; /* b00000111: internal clock, 1/256 prescaler */  
	INTCONbits.TMR0IF = 0;
	INTCONbits.TMR0IE = 0; /* no interrupt */
	T0CONbits.TMR0ON = 1;

#if 0
	/* configure UART for 57600Bps at 48Mhz */
	SPBRG1 = 12;
#endif
	/* configure UART for 921600Bps at 48Mhz */
	TXSTA1bits.BRGH = 1;
	BAUDCON1bits.BRG16 = 1;
	SPBRGH1 = 0;
	SPBRG1 = 12;

	USART_INIT(0);
	stdout = STREAM_USER; /* Use the macro PUTCHAR with printf */

#if TIMER2_10HZ == 100
	/* configure timer2 for 1Khz interrupt */
	T2CON = 0x22; /* b00100010: postscaller 1/5, prescaler 1/16 */
	PR2 = 150; /* 1khz output */
#elif TIMER2_10HZ == 1000
	/* configure timer2 for 10Khz interrupt */
	T2CON = 0x22; /* b00100010: postscaller 1/5, prescaler 1/16 */  
	PR2 = 15; /* 10khz output */
#elif TIMER2_10HZ == 2000
	/* configure timer2 for 20Khz interrupt */
	T2CON = 0x21; /* b00100001: postscaller 1/5, prescaler 1/4 */ 
	PR2 = 29; /* 20khz output */
#else 
#error "unknown TIMER2_10HZ"
#endif
	counter_10hz = TIMER2_10HZ;
	T2CONbits.TMR2ON = 1;
	PIR1bits.TMR2IF = 0;
	IPR1bits.TMR2IP = 1; /* high priority interrupt */
	PIE1bits.TMR2IE = 1;


	INTCONbits.GIE_GIEH=1;  /* enable high-priority interrupts */   
	INTCONbits.PEIE_GIEL=1; /* enable low-priority interrrupts */   

	/*
	 * configure ADC:
	 * AN3: vref+
	 * AN2: I
	 * AN1: vout
	 */

	ADCON0 = 0xc1; /* b11000001 */
	/* clk = fosc/64, tacq = 4tad (5.33us) */
	ADCON1 = 0x96; /* b10010110 */
	/* ANCON already set up */

	/* start calibration */
	ADCON1bits.ADCAL = 1;
	ADCON0bits.GO_NOT_DONE =1;
	while (ADCON0bits.GO_NOT_DONE)
		; /* wait */
	ADCON1bits.ADCAL = 0;
	PIR1bits.ADIF = 0;
	PIE1bits.ADIE = 1;

	printf("hello world\n");
	/* enable watch dog timer */  
	WDTCON = 0x01;

	printf("\nready\n");
	/* start I calibration process */
	ad_channel = 0;
	ADCON0bits.CHS = 0;
	softintrs &= ~INT_DOAD;
	PORTCbits.RC1 = 1;
	PORTCbits.RC2 = 0;

again:
	while (1) {
		CLRWDT;
		if (softintrs & INT_AD) {
			softintrs &= ~INT_AD;
			if (ad_channel == 0) {
				PRINTHEX(PORTB & 0xf);
				PRINTHEX(ADRESH & 0xf);
				PRINTHEX(ADRESL >> 4);
				PRINTHEX(ADRESL & 0xf);

				//printf("%1x%3x", (PORTB & 0xf), ADRESL | (ADRESH << 8));
				/*
				 * needs 2Tac, or 32 instrutions
				 * before next sample. assume we
				 * already have them since the
				 * interrupt
				 */
				ad_channel = 1;
				ADCON0bits.CHS = 1;
			} else {
				ad_channel = 0;
				ADCON0bits.CHS = 0;
				PRINTHEX(ADRESH & 0xf);
				PRINTHEX(ADRESL >> 4);
				PRINTHEX(ADRESL & 0xf);
				putchar('X');
				//printf("%3xX", ADRESL | (ADRESH << 8));
			}
		}

		if ((softintrs & INT_AD) == 0 &&
	            (softintrs & INT_DOAD) && 
		    ADCON0bits.GO_NOT_DONE == 0) {
			ADCON0bits.GO_NOT_DONE = 1;
			softintrs &= ~INT_DOAD;
		}

		if (RCREG1 == 'r')
			break;
		SLEEP;

	}

end:

	while ((c = getchar()) != 'r') {
		printf("got %c\n", c);
		goto again;
	}
	printf("returning\n");
	while (PIE1bits.TX1IE)
		; /* wait for transmit to complete */
	INTCONbits.PEIE=0; /* disable peripheral interrupts */
	INTCONbits.GIE=0;  /* disable interrrupts */
}

unsigned int
timer0_read() __naked   
{
	/* return TMR0L | (TMR0H << 8), reading TMR0L first */
	__asm   
	movf    _TMR0L, w
	movff   _TMR0H, _PRODL
	return
	__endasm;       
}

/* Vectors */
void _reset (void) __naked __interrupt 0
{
	__asm__("goto __startup");
}


void _startup (void) __naked
{

  __asm
    // Initialize the stack pointer
    lfsr 1, _stack_end
    lfsr 2, _stack_end
    clrf _TBLPTRU, 0    // 1st silicon doesn't do this on POR
    
    // initialize the flash memory access configuration. this is harmless
    // for non-flash devices, so we do it on all parts.
    bsf _EECON1, 7, 0
    bcf _EECON1, 6, 0
    __endasm ;

  /* Call the user's main routine */
  main();
  __asm__("reset");
}

/*
 * high priority interrupt. Split in 2 parts; one for the entry point
 * where we'll deal with timer0, then jump to another address
 * as we don't have enough space before the low priority vector
 */
void _irqh (void) __naked __shadowregs __interrupt 1
{
	__asm
	bcf   _PIR1, 1
	goto _irqh_timer2
	__endasm ;

}

void irqh_timer2(void) __naked
{
	/*
	 * no sdcc registers are automatically saved,
	 * so we have to be carefull with C code !
	 */
#if 0
	counter_10hz--;
	if (counter_10hz == 0) {
		counter_10hz = TIMER2_10HZ;
		softintrs |= INT_10HZ;
	}			     
#endif
	if (softintrs & INT_DOAD) {
		PORTCbits.RC2=1;
	}
	softintrs |= INT_DOAD;
	__asm
	retfie 1
	nop
	__endasm;
}

void _irq (void) __interrupt 2 /* low priority */
{
	USART_INTR;
	if (PIE1bits.ADIE && PIR1bits.ADIF) {
		PIR1bits.ADIF = 0;
		softintrs |= INT_AD;
	}
}