#include <stdint.h>
#include <stdbool.h>

#include "user.h"

#include "ws2811.h"

/* this holds the G R B bytes for the entire string */
unsigned char rgbdata[RGB_COUNT];


/* These values are placed in common memory so that they can be accessed
 * quickly without a bank switch by the routines below, THIS IS IMPORTANT,
 * it will not run properly without it */
volatile uint8_t rgb_sample @ 0x7B;
volatile uint8_t rgb_byte @ 0x7C;
volatile uint8_t rgb_bit @ 0x7D;

// send the whole pile of data
static void ws2811_send(void)
{
#asm
    // copy the led colour array location into FSR0 for fast access
    MOVLW HIGH _rgbdata
    MOVWF FSR0H
    MOVLW LOW _rgbdata
    MOVWF FSR0L

    // load next byte from array into working reg
ws2811_nextbyte:
    MOVIW FSR0++
    MOVWF _rgb_sample
    MOVLW 8 // reset bit count
    MOVWF _rgb_bit

ws2811_sendbit:
    // you assume its a zero then test if its one
//    MOVLW 0xC0 ;11000000B
    MOVLW 0x80 ;10000000B
    
    RLF _rgb_sample,f
    BTFSC STATUS,0  // CARRY
    //asm("MOVLW 0xF8 "); // 11111000B
    MOVLW 0xF0      // 11110000B

    BANKSEL (SSP1BUF)
    MOVWF BANKMASK(SSP1BUF)

    // any more bits
    DECFSZ _rgb_bit,f
    BRA ws2811_delay

    // any more bytes
    DECFSZ _rgb_byte,f
    BRA ws2811_nextbyte
    BRA ws2811_end

ws2811_delay:
    NOP
    NOP
    NOP
    BRA ws2811_sendbit

ws2811_end:


#endasm

    // all done
}

#if _XTAL_FREQ != 32000000L
#error "This code requires 32MHz system clock or above"
#endif

void ws2811_init(void)
{
    // SPI is on RA0
    TRISAbits.TRISA0 = 0; // SDO is RA0
    ANSELAbits.ANSA0 = 0; // not analog

    // SCK (SPI Clock) is RA1
    // SDI (SPI In) is RA2
    APFCONbits.SDOSEL = 0; // use RA0 not RA4 for output

    // at 8MHz Tclk   0 = 2 bits, 1 = 6 bits.
    // write to SSP1BUF
    SSP1CON1bits.SSPM = 0b0000; // SPI Master Fosc/4
    SSP1CON1bits.SSPEN = 1; // enable MSSP
}

void ws2811_transmit(void)
{
    rgb_byte = RGB_COUNT;
    ws2811_send(); // send the first bit
}