void
writebyte( libspectrum_word address, libspectrum_byte b )
{
printf( "%5d MC %04x\n", tstates, address );
tstates += 3;
writebyte_internal( address, b );
}
void
writebyte( libspectrum_word address, libspectrum_byte b )
{
libspectrum_word bank;
memory_page *mapping;
bank = address >> 13;
mapping = &memory_map_write[ bank ];
if( debugger_mode != DEBUGGER_MODE_INACTIVE )
debugger_check( DEBUGGER_BREAKPOINT_TYPE_WRITE, address );
if( mapping->contended ) tstates += ula_contention[ tstates ];
tstates += 3;
writebyte_internal( address, b );
}
static int
trap_load_block( libspectrum_tape_block *block )
{
libspectrum_byte parity, *data;
int i = 0, length, read, verify;
/* On exit:
* A = calculated parity byte if parity checked, else 0 (CHECKME)
* F : if parity checked, all flags are modified
* else carry only is modified (FIXME)
* B = 0xB0 (success) or 0x00 (failure)
* C = 0x01 (confirmed), 0x21, 0xFE or 0xDE (CHECKME)
* DE : decremented by number of bytes loaded or verified
* H = calculated parity byte or undefined
* L = last byte read, or 1 if none
* IX : incremented by number of bytes loaded or verified
* A' = unchanged on error + no flag byte, else 0x01
* F' = 0x01 on error + no flag byte, else 0x45
* R = no point in altering it :-)
* Other registers unchanged.
*/
data = libspectrum_tape_block_data( block );
length = libspectrum_tape_block_data_length( block );
/* Number of bytes to load or verify */
read = length - 1;
if( read > DE )
read = DE;
/* If there's no data in the block (!), set L then error exit.
* We don't need to alter H, IX or DE here */
if( !length ) {
L = F_ = 1;
F &= ~FLAG_C;
return 0;
}
verify = !(F_ & FLAG_C);
i = A_; /* i = A' (flag byte) */
AF_ = 0x0145;
A = 0;
/* Initialise the parity check and L to the block ID byte */
L = parity = *data++;
/* If the block ID byte != the flag byte, clear carry and return */
if( parity != i )
goto error_ret;
/* Now set L to the *last* byte in the block */
L = data[read - 1];
/* Loading or verifying determined by the carry flag of F' */
if( verify ) { /* verifying */
for( i = 0; i < read; i++ ) {
parity ^= data[i];
if( data[i] != readbyte_internal(IX+i) ) {
/* Verification failure */
L = data[i];
goto error_ret;
}
}
} else {
for( i = 0; i < read; i++ ) {
parity ^= data[i];
writebyte_internal( IX+i, data[i] );
}
}
/* At this point, i == number of bytes actually read or verified */
/* If |DE| bytes have been read and there's more data, do the parity check */
if( DE == i && read + 1 < length ) {
parity ^= data[read];
A = parity;
CP( 1 ); /* parity check is successful if A==0 */
B = 0xB0;
} else {
/* Failure to read first bit of the next byte (ref. 48K ROM, 0x5EC) */
B = 255;
L = 1;
INC( B );
error_ret:
F &= ~FLAG_C;
}
/* At this point, AF, AF', B and L are already modified */
C = 1;
H = parity;
DE -= i;
IX += i;
return 0;
}
/* Poke a value into RAM */
int
debugger_poke( libspectrum_word address, libspectrum_byte value )
{
writebyte_internal( address, value );
return 0;
}
