#include <16F88.h>

#fuses HS, NOLVP, NOWDT, PUT, NOPROTECT, NOBROWNOUT, MCLR
#use delay (clock=20000000)
#use fast_io(A)
#use fast_io(B)

/* hsync interval */
#define H_INTERVAL 0xFEEF

/* sync bit */
int1  bSync;
#bit  bSync = 5.0

/* video */
int8  cVid;
#byte cVid  = 6

/* 32bit * 60line */
int8  Lines0[60],Lines1[60],Lines2[60],Lines3[60];
const int8* Lines[4] = {Lines0,Lines1,Lines2,Lines3};
int8* p;
int8  v0,v1,v2,v3;

#define PUT_32BIT \
    cVid  = v0; delay_cycles(2); cVid <<= 1; delay_cycles(2);\
    cVid <<= 1; delay_cycles(2); cVid <<= 1; delay_cycles(2);\
    cVid <<= 1; delay_cycles(2); cVid <<= 1; delay_cycles(2);\
    cVid <<= 1; delay_cycles(2); cVid <<= 1; delay_cycles(2);\
    cVid  = v1; delay_cycles(2); cVid <<= 1; delay_cycles(2);\
    cVid <<= 1; delay_cycles(2); cVid <<= 1; delay_cycles(2);\
    cVid <<= 1; delay_cycles(2); cVid <<= 1; delay_cycles(2);\
    cVid <<= 1; delay_cycles(2); cVid <<= 1; delay_cycles(2);\
    cVid  = v2; delay_cycles(2); cVid <<= 1; delay_cycles(2);\
    cVid <<= 1; delay_cycles(2); cVid <<= 1; delay_cycles(2);\
    cVid <<= 1; delay_cycles(2); cVid <<= 1; delay_cycles(2);\
    cVid <<= 1; delay_cycles(2); cVid <<= 1; delay_cycles(2);\
    cVid  = v3; delay_cycles(2); cVid <<= 1; delay_cycles(2);\
    cVid <<= 1; delay_cycles(2); cVid <<= 1; delay_cycles(2);\
    cVid <<= 1; delay_cycles(2); cVid <<= 1; delay_cycles(2);\
    cVid <<= 1; delay_cycles(2); cVid <<= 1; delay_cycles(2);

/* vertical sync */
int1  LineField = 0;
int8  LineIdx   = 0;
void VerticalSync(){
    delay_cycles(2);
    /* 286:525 or 23:262 */
    do{
        bSync = 0; delay_us(4);
        bSync = 1;
        disable_interrupts(INT_TIMER1);
        p = Lines[LineIdx >> 6];
        p += (LineIdx & 0x3C);
        v0 = *p; p++; v1 = *p; p++;
        v2 = *p; p++; v3 = *p;
        PUT_32BIT
        cVid = 0; delay_cycles(60);
        if((LineIdx & 0x3F) != 59){
            LineIdx += 1;
        }else{
            LineIdx += 5;
            delay_cycles(1);
        }
    }while(LineIdx != 0);

    // 1:9 or 263:271
    LineIdx = (LineField) ? 7:6;
    do{
        bSync = 0; delay_us(4);
        bSync = 1; delay_cycles(132);
        LineIdx--;
    }while(LineIdx != 0);
    LineField++;
    do{
        bSync = 0; delay_us(27);
        bSync = 1; delay_cycles(16);
        LineIdx++;
    }while(LineIdx < 6);
    LineIdx = (LineField) ? 6:5;
    do{
        bSync = 0; delay_us(4);
        bSync = 1; delay_cycles(132);
        LineIdx--;
    }while(LineIdx != 0);

    // 10 or 272
    delay_cycles(1);
    bSync = 0; delay_us(4);
    bsync = 1;
    // 11:22 or 273:285
    LineIdx = (LineField) ? 12:13;
    set_timer1(0xFF0F);
    enable_interrupts(INT_TIMER1);
}

#int_timer1
void timer1_isr(){
    if(LineIdx == 0){
        VerticalSync();
    }else{
        set_timer1(H_INTERVAL);
        bSync = 0;
        delay_us(4);
        bSync = 1;
        LineIdx--;
    }
}

void main(){
    int8 i;
    /* A/D */
    setup_adc_ports(NO_ANALOGS);

    /* port */
    set_tris_a(0x00); output_A(0x00);
    set_tris_b(0x00); output_B(0x00);

    /* set image */
    for(i = 0; i < 60; i++){
        Lines0[i] = 0xFF;
        Lines1[i] = 0xFF;
        Lines2[i] = 0xFF;
        Lines3[i] = 0xFF;
    }
    Lines1[57] ^= 0x1F; Lines1[58] ^= 0xE0;
    Lines2[ 1] ^= 0x7C; Lines2[ 2] ^= 0x18;
    Lines2[ 5] ^= 0xF3; Lines2[ 6] ^= 0xFE;
    Lines2[ 9] ^= 0x4C; Lines2[10] ^= 0x07;
    Lines2[13] ^= 0x30; Lines2[14] ^= 0x03;
    Lines2[17] ^= 0x63; Lines2[18] ^= 0x99;
    Lines2[21] ^= 0xC4; Lines2[22] ^= 0x90;
    Lines2[25] ^= 0xC5; Lines2[26] ^= 0x90;
    Lines2[29] ^= 0x40; Lines2[30] ^= 0x00;
    Lines2[33] ^= 0x00; Lines2[34] ^= 0x00;
    Lines2[37] ^= 0x05; Lines2[38] ^= 0xE0;
    Lines2[41] ^= 0x01; Lines2[42] ^= 0xF0;
    Lines2[45] ^= 0x09; Lines2[46] ^= 0x08;
    Lines2[49] ^= 0x1E; Lines2[50] ^= 0x0C;
    Lines2[53] ^= 0x0F; Lines2[54] ^= 0xF8;
    Lines2[57] ^= 0x03; Lines2[58] ^= 0xE0;

    /* timer */
    setup_timer_1(T1_INTERNAL | T1_DIV_BY_1);
    set_timer1(H_INTERVAL);
    enable_interrupts(INT_TIMER1);
    enable_interrupts(GLOBAL);

    while(TRUE);
}