///////////////////////////////////////////////////////////////////////////
//// Library for a MicroChip 93C66B configured for a x16 org ////
//// ////
//// init_ext_eeprom(); Call before the other functions are used ////
//// ////
//// write_ext_eeprom(a, d); Write the byte d to the address a ////
//// ////
//// d = read_ext_eeprom(a); Read the byte d from the address a ////
//// ////
//// The main program may define eeprom_select, eeprom_di, eeprom_do ////
//// and eeprom_clk to override the defaults below. ////
//// ////
///////////////////////////////////////////////////////////////////////////
//// (C) Copyright 1996,2003 Custom Computer Services ////
//// This source code may only be used by licensed users of the CCS C ////
//// compiler. This source code may only be distributed to other ////
//// licensed users of the CCS C compiler. No other use, reproduction ////
//// or distribution is permitted without written permission. ////
//// Derivative programs created using this software in object code ////
//// form are not restricted in any way. ////
///////////////////////////////////////////////////////////////////////////

#ifndef EEPROM_SELECT

#define EEPROM_SELECT PIN_C0
#define EEPROM_CLK PIN_C1
#define EEPROM_DI PIN_C2
#define EEPROM_DO PIN_C3

#endif

#define EEPROM_ADDRESS long int
#define EEPROM_SIZE 512

#define hi(x) (*(&x+1))


void init_ext_eeprom() {
BYTE cmd[2];
BYTE i;

output_low(EEPROM_DI);
output_low(EEPROM_CLK);
output_low(EEPROM_SELECT);

cmd[0]=0xc0;
cmd[1]=0x4;

for(i=1;i<=5;++i)
shift_left(cmd,2,0);
output_high(EEPROM_SELECT);
for(i=1;i<=11;++i) {
output_bit(EEPROM_DI, shift_left(cmd,2,0));
output_high(EEPROM_CLK);
output_low(EEPROM_CLK);
}
output_low(EEPROM_DI);
output_low(EEPROM_SELECT);
}


void write_ext_eeprom(EEPROM_ADDRESS address, long data) {
BYTE cmd[3];
BYTE i;

cmd[0]=data;
cmd[1]=(BYTE)address;
cmd[2]=0xa|hi(address);

for(i=1;i<=4;++i)
shift_left(cmd,3,0);
output_high(EEPROM_SELECT);
for(i=1;i<=27;++i) {
if(i==4)
output_high(EEPROM_SELECT);
output_bit(EEPROM_DI, shift_left(cmd,3,0));
output_high(EEPROM_CLK);
output_low(EEPROM_CLK);
}
output_low(EEPROM_DI);
output_low(EEPROM_SELECT);
delay_ms(11);
}


BYTE read_ext_eeprom(EEPROM_ADDRESS address) {
BYTE cmd[3];
BYTE i;
long data;

cmd[0]=0;
cmd[1]=(BYTE)address;
cmd[2]=0xc|hi(address);

for(i=1;i<=4;++i)
shift_left(cmd,3,0);
output_high(EEPROM_SELECT);
for(i=1;i<=27;++i) {
output_bit(EEPROM_DI, shift_left(cmd,3,0));
output_high(EEPROM_CLK);
output_low(EEPROM_CLK);
if(i>11)
shift_left(&data,1,input(EEPROM_DO));
}
output_low(EEPROM_SELECT);
return(data);
}