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//---------------------------------------------------------------------------------------

//      Project:                        light8080 SOC           WiCores Solutions 

//

//      File name:                      hello.c                                 (February 04, 2012)

//

//      Writer:                         Moti Litochevski 

//

//      Description:

//              This file contains a simple program written in Small-C that sends a string to 

//              the UART and then switches to echo received bytes. 

//              This example also include a simple interrupt example which will work with the 

//              verilog testbench. the testbench 

//

//      Revision History:

//

//      Rev <revnumber>                 <Date>                  <owner> 

//              <comment>

//---------------------------------------------------------------------------------------

// define interrupt vectors 

// note that this file must be edited to enable interrupt used 

#include intr_vec.h 

// insert c80 assmbly library to the output file 

#include ..\tools\c80\c80.lib

// UART IO registers 

port (128) UDATA;               // uart data register used for both transmit and receive 

port (129) UBAUDL;              // low byte of baud rate register 

port (130) UBAUDH;              // low byte of baud rate register 

port (131) USTAT;               // uart status register 

// digital IO ports registers 

port (132) P1DATA;      // port 1 data register 

port (133) P1DIR;               // port 1 direction register control 

port (134) P2DATA;              // port 2 data register 

port (135) P2DIR;               // port 2 direction register control 

// interrupt controller register 

port (136) INTRENA;             // interrupts enable register 

// simulation end register 

// writing any value to this port will end the verilog simulation when using tb_l80soc 

// test bench. 

port (255) SIMEND;

// registers bit fields definition 

// uart status register decoding 

#define UTXBUSY         1

#define URXFULL         16

// globals 

char rxbyte;            // byte received from the uart 

int tstary[2] = {1234, 5678};

//---------------------------------------------------------------------------------------

// send a single byte to the UART 

sendbyte(by)

char by;

{

        while (USTAT & UTXBUSY);

        UDATA = by;

}

// check if a byte was received by the uart 

getbyte()

{

        if (USTAT & URXFULL) {

                rxbyte = UDATA;

                return 1;

        }

        else

                return 0;

}

// send new line to the UART 

nl()

{

        sendbyte(13);

        sendbyte(10);

}

// sends a string to the UART 

printstr(sptr)

char *sptr;

{

        while (*sptr != 0)

                sendbyte(*sptr++);

}

// sends a decimal value to the UART 

printdec(dval)

int dval;

{

        if (dval<0) {

                sendbyte('-');

                dval = -dval;

        }

        outint(dval);

}

// function copied from c80dos.c 

outint(n)

int n;

{

int q;

        q = n/10;

        if (q) outint(q);

        sendbyte('0'+(n-q*10));

}

// sends a hexadecimal value to the UART 

printhex(hval)

int hval;

{

int q;

        q = hval/16;

        if (q) printhex(q);

        q = hval-q*16;

        if (q > 9)

                sendbyte('A'+q-10);

        else

                sendbyte('0'+q);

}

// external interrupt 0 service routine 

int0_isr()

{

        printstr("Interrupt 0 was asserted."); nl();

}

// program main routine 

main()

{

        // configure UART baud rate - set to 9600 for 30MHz clock 

        // BAUD = round(<clock>/<baud rate>/16) = round(30e6/9600/16) = 195 

        // Note: Usage of a minimum divider value of 1 will accelerate the RTL simulation. 

        UBAUDL = 195;

        UBAUDH = 0;

        // configure both ports to output and digital outputs as zeros 

        P1DATA = 0x00;

        P1DIR = 0xff;

        P2DATA = 0x00;

        P2DIR = 0xff;

        // enable interrupt 0 only 

        INTRENA = 0x01;

        // enable CPU interrupt 

#asm 

        ei

#endasm

        // print message 

        printstr("Hello World!!!"); nl();

        printstr("Dec value: "); printdec(tstary[1]); nl();

        printstr("Hex value: 0x"); printhex(tstary[0]); nl();

        // assert bit 0 of port 1 to test external interrupt 0 

        P1DATA = 0x01;

        printstr("Echoing received bytes: "); nl();

        // loop forever 

        while (1) {

                // check if a new byte was received 

                if (getbyte())

                        // echo the received byte to the UART 

                        sendbyte(rxbyte);

        }

}

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//                                              Th.. Th.. Th.. Thats all folks !!!

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