jay.c

__xdata struct { uint8_t r [ 252 ], t [ 124 ]; } jay_buf;
        struct { uint8_t r,         t;         } jay_ind, jay_len;
uint16_t jay_numbits;

const uint8_t jay_caps     [ 4 ] = { 3, 8, 2 };         /* hw_ver free_mem sel_if */
const uint8_t jay_free_mem [ 4 ] = { 0xFC };            /* 252 */
const uint8_t jay_hw_stat  [ 8 ] = { 5, 0xD };          /* 3333 */
const uint8_t jay_hw_ver   [ 4 ] = { 0xD1, 0x2F, 1 };   /* 77777 */
const uint8_t jay_sel_if   [ 4 ] = { 2 };               /* mask */
const uint8_t jay_ver   [ 0x22 ] = "\x20\x00Jay CH55x";

void jay_init ( void ) {
    GPIO_SWCLOCK( 0 );
    GPIO_SWCLOCK_MODE();
    GPIO_SWDIN_MODE();
    jay_ind.r = jay_len.r = 0;
    jay_ind.t = jay_len.t = 0;
}

void jay_reply ( uint8_t *buf, uint8_t len ) {
    jay_ind.t = jay_len.t = 0;
    for( uint8_t i = 0; i < len; i++ ) jay_buf.t[ jay_len.t++ ] = buf[ i ];
}

uint8_t jay_protocol ( void ) {
    switch( jay_buf.r[ 0 ] ) {
        case 0x01 : jay_reply( jay_ver, sizeof( jay_ver ));
                    break;
        case 0x07 : jay_reply( jay_hw_stat, sizeof( jay_hw_stat ));
                    break;
        case 0xC7 : jay_reply( jay_sel_if, sizeof( jay_sel_if ));
                    if( jay_buf.r[ 1 ] != 0xFF ) jay_buf.t[ 0 ] = 1;
                    break;
        case 0xCF : jay_numbits = *(( uint16_t* ) &jay_buf.r[ 2 ] );
                    return 4 + 2 * (( jay_numbits + 7 ) >> 3 );
        case 0xD4 : jay_reply( jay_free_mem, sizeof( jay_free_mem ));
                    break;
        case 0xDC : GPIO_RESET( 0 );
                    break;
        case 0xDD : GPIO_RESET( 1 );
                    break;
        case 0xE8 : jay_reply( jay_caps, sizeof( jay_caps ));
                    break;
        case 0xF0 : jay_reply( jay_hw_ver, sizeof( jay_hw_ver ));
    }
    return 0;
}

void jay_swd ( void ) {
    uint8_t dir, in, mask, out;
    dir = in = mask = out = 0;
    jay_ind.r = 4;
    jay_len.r = 4 + (( jay_numbits + 7 ) >> 3 );
    jay_ind.t = jay_len.t = 0;
    while( jay_numbits-- ) {
        if( mask == 0 ) {
            mask = 1;
            dir = jay_buf.r[ jay_ind.r++ ];
            out = jay_buf.r[ jay_len.r++ ];
            in = 0;
        }
        if( dir & mask ) {
            GPIO_SWDOUT_MODE();
            GPIO_SWDOUT( out & mask );
        } else {
            GPIO_SWDIN_MODE();
        }
        GPIO_SWCLOCK( 0 ); GPIO_DELAY();
        GPIO_SWCLOCK( 1 ); GPIO_DELAY();
        in |= GPIO_SWDIN() ? mask : 0;
        mask <<= 1;
        if( mask == 0 ) jay_buf.t[ jay_len.t++ ] = in;
    }
    if( mask ) jay_buf.t[ jay_len.t++ ] = in;
    jay_buf.t[ jay_len.t++ ] = 0;
    GPIO_SWCLOCK( 0 );
}

void jay_poll ( uint8_t *rbuf, uint8_t *rlen, uint8_t *tbuf, uint8_t *tlen ) {
    uint8_t i, len;
    if( jay_len.t ) {
        if( *tlen == 0 ) {
            len = jay_len.t - jay_ind.t;
            if( len > 64 ) len = 64; else if( len > 1 ) len--;
            for( i = 0; i < len; i++ ) tbuf[ i ] = jay_buf.t[ jay_ind.t++ ];
            if( jay_ind.t >= jay_len.t ) jay_ind.t = jay_len.t = 0;
            *tlen = len;
        }
    } else if( *rlen ) {
        len = *rlen;
        for( i = 0; i < len; i++ ) jay_buf.r[ jay_ind.r++ ] = rbuf[ i ];
        if( jay_len.r == 0 ) jay_len.r = jay_protocol();
        if( jay_ind.r >= jay_len.r ) {
            if( jay_buf.r[ 0 ] == 0xCF ) jay_swd();
            jay_ind.r = jay_len.r = 0;
        }
        *rlen = 0;
    }
}