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

extern void PUT32 ( unsigned int, unsigned int );
extern void PUT16 ( unsigned int, unsigned int );
extern void PUT8 ( unsigned int, unsigned int );
extern unsigned int GET32 ( unsigned int );
extern void BRANCHTO ( unsigned int );
extern void dummy ( unsigned int );

#define ARM_TIMER_CTL 0x2000B408
#define ARM_TIMER_CNT 0x2000B420

#define GPFSEL1 0x20200004
#define GPSET0  0x2020001C
#define GPCLR0  0x20200028
#define GPPUD       0x20200094
#define GPPUDCLK0   0x20200098

#define AUX_ENABLES     0x20215004
#define AUX_MU_IO_REG   0x20215040
#define AUX_MU_IER_REG  0x20215044
#define AUX_MU_IIR_REG  0x20215048
#define AUX_MU_LCR_REG  0x2021504C
#define AUX_MU_MCR_REG  0x20215050
#define AUX_MU_LSR_REG  0x20215054
#define AUX_MU_MSR_REG  0x20215058
#define AUX_MU_SCRATCH  0x2021505C
#define AUX_MU_CNTL_REG 0x20215060
#define AUX_MU_STAT_REG 0x20215064
#define AUX_MU_BAUD_REG 0x20215068

//GPIO14  TXD0 and TXD1
//GPIO15  RXD0 and RXD1
//------------------------------------------------------------------------
unsigned int uart_recv ( void )
{
    while(1)
    {
        if(GET32(AUX_MU_LSR_REG)&0x01) break;
    }
    return(GET32(AUX_MU_IO_REG)&0xFF);
}
//------------------------------------------------------------------------
void uart_send ( unsigned int c )
{
    while(1)
    {
        if(GET32(AUX_MU_LSR_REG)&0x20) break;
    }
    PUT32(AUX_MU_IO_REG,c);
}
//------------------------------------------------------------------------
void hexstrings ( unsigned int d )
{
    //unsigned int ra;
    unsigned int rb;
    unsigned int rc;

    rb=32;
    while(1)
    {
        rb-=4;
        rc=(d>>rb)&0xF;
        if(rc>9) rc+=0x37; else rc+=0x30;
        uart_send(rc);
        if(rb==0) break;
    }
    uart_send(0x20);
}
//------------------------------------------------------------------------
void hexstring ( unsigned int d )
{
    hexstrings(d);
    uart_send(0x0D);
    uart_send(0x0A);
}
//------------------------------------------------------------------------
unsigned char xstring[256];
//------------------------------------------------------------------------
int notmain ( void )
{
    unsigned int ra;
    //unsigned int rb;
    unsigned int rx;
    unsigned int addr;
    unsigned int block;
    unsigned int state;

    unsigned int crc;

    PUT32(AUX_ENABLES,1);
    PUT32(AUX_MU_IER_REG,0);
    PUT32(AUX_MU_CNTL_REG,0);
    PUT32(AUX_MU_LCR_REG,3);
    PUT32(AUX_MU_MCR_REG,0);
    PUT32(AUX_MU_IER_REG,0);
    PUT32(AUX_MU_IIR_REG,0xC6);
    PUT32(AUX_MU_BAUD_REG,270);
    ra=GET32(GPFSEL1);
    ra&=~(7<<12); //gpio14
    ra|=2<<12;    //alt5
    ra&=~(7<<15); //gpio15
    ra|=2<<15;    //alt5
    PUT32(GPFSEL1,ra);
    PUT32(GPPUD,0);
    for(ra=0;ra<150;ra++) dummy(ra);
    PUT32(GPPUDCLK0,(1<<14)|(1<<15));
    for(ra=0;ra<150;ra++) dummy(ra);
    PUT32(GPPUDCLK0,0);
    PUT32(AUX_MU_CNTL_REG,3);

    PUT32(ARM_TIMER_CTL,0x00F90000);
    PUT32(ARM_TIMER_CTL,0x00F90200);

    hexstring(0x12345678);

//SOH 0x01
//ACK 0x06
//NAK 0x15
//EOT 0x04

//block numbers start with 1

//132 byte packet
//starts with SOH
//block number byte
//255-block number
//128 bytes of data
//checksum byte (whole packet)
//a single EOT instead of SOH when done, send an ACK on it too

    block=1;
    addr=0;
    state=0;
    rx=GET32(ARM_TIMER_CNT);
    while(1)
    {
        ra=GET32(ARM_TIMER_CNT);
        if((ra-rx)>=4000000)
        {
            uart_send(0x15);
            rx+=4000000;
        }
        if((GET32(AUX_MU_LSR_REG)&0x01)==0) continue;
        xstring[state]=GET32(AUX_MU_IO_REG)&0xFF;
        rx=GET32(ARM_TIMER_CNT);
        if(state==0)
        {
            if(xstring[state]==0x04)
            {
                uart_send(0x06);
                BRANCHTO(0);
                break;
            }
        }
        switch(state)
        {
            case 0:
            {
                if(xstring[state]==0x01)
                {
                    crc=xstring[state];
                    state++;
                }
                else
                {
                    //state=0;
                    uart_send(0x15);
                }
                break;
            }
            case 1:
            {
                if(xstring[state]==block)
                {
                    crc+=xstring[state];
                    state++;
                }
                else
                {
                    state=0;
                    uart_send(0x15);
                }
                break;
            }
            case 2:
            {
                if(xstring[state]==(0xFF-xstring[state-1]))
                {
                    crc+=xstring[state];
                    state++;
                }
                else
                {
                    uart_send(0x15);
                    state=0;
                }
                break;
            }
            case 131:
            {
                crc&=0xFF;
                if(xstring[state]==crc)
                {
                    for(ra=0;ra<128;ra++)
                    {
                        PUT8(addr++,xstring[ra+3]);
                    }
                    uart_send(0x06);
                    block=(block+1)&0xFF;
                }
                else
                {
                    uart_send(0x15);
                }
                state=0;
                break;
            }
            default:
            {
                crc+=xstring[state];
                state++;
                break;
            }
        }
    }
    return(0);
}
//-------------------------------------------------------------------------
//-------------------------------------------------------------------------