#include "display.h"


//                      7 segment table

prog_uint8_t chartab[] = { _0, _1, _2, _3, _4, _5, _6, _7, _8, _9 };

uint8_t display_buff[3*7];


                        // decimal output -999 ... 999
                        // dp == 2: "9.99"
                        // dp == 1: "99.9"
void valout( int16_t val, uint8_t channel, uint8_t dp )
{
  uint8_t ones, tens, hundreds;
  uint8_t *sspt;  
  uint8_t *pt;

  if( channel >= sizeof(display_buff) / 3 )
    return;
  ones = 0;
  if( val < 0 ){
    val = -val;
    ones = MINUS3;                      // minus sign
  }
  if( val > 999 ){
    hundreds = CHAR_E;                  // "Err"
    tens = CHAR_r;
    ones += CHAR_r;                     // "-Err"
  }else{
    sspt = chartab - 1;
    do{
      val -= 100;
      sspt++;
    }while( val >= 0 );
    hundreds = pgm_read_byte( sspt );
    sspt = chartab + 10;
    do{
      val += 10;
      sspt--;
    }while( val < 0 );
    tens = pgm_read_byte( sspt );
    if( dp == 1 )                       // insert decimal point
      tens |= _DP;
    else if( dp == 2 )
      hundreds |= _DP;                  // insert decimal point
    if( hundreds == _0 ){               // check leading zero
      hundreds = SPACE;                 // blank leading zero
      if( tens == _0 ){                 // check leading zero
        tens = SPACE;                   // blank leading zero
      }
      if( ones == MINUS3 ){             // move minus sign
        ones = 0;
        if( tens == SPACE )
          tens = MINUS;
        else
          hundreds = MINUS;
      }
    }
    ones |= pgm_read_byte( chartab + val );
  }
  pt = display_buff + 3 * channel;
  *pt++ = ones;
  *pt++ = tens;
  *pt++ = hundreds;
}


static void spi_out( uint8_t val )
{
  for( uint8_t i = 8; i; i-- ){
    SDO = 0;
    if( val & 0x80 )
      SDO = 1;
    SSCK = 0;
    val <<= 1;
    SSCK = 1;
  }
}


void display_update()
{
  uint8_t *pt = display_buff;

  SSCK_DDR = 1; 
  SDO_DDR = 1; 
  LOAD_DDR = 1;
  OEN = 1; 
  OEN_DDR = 1; 
  LOAD = 0;
  for( uint8_t i = sizeof(display_buff); i; i-- )
    spi_out( ~*pt++ );                                  // low active 
  LOAD = 1;
  OEN = 0;
}