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Started working CRC checking into the 1770. Discovered immediately that my generated CRC does not match that built into the Oric disk images. So mine is pretty-much certainly wrong. An opportunity for learning!

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This commit is contained in:
Thomas Harte
2016-12-26 16:46:26 -05:00
parent 0490a47058
commit 9c0f622a2e
2 changed files with 20 additions and 4 deletions
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Components/1770/1770.cpp
+16 -4
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@@ -29,6 +29,7 @@ WD1770::Status::Status() :
WD1770::WD1770(Personality p) :
Storage::Disk::Controller(8000000, 16, 300),
crc_generator_(0x1021, 0xffff),
interesting_event_mask_(Event::Command),
resume_point_(0),
delay_time_(0),
@@ -563,6 +564,7 @@ void WD1770::posit_event(Event new_event_type)
});
distance_into_section_ = 0;
is_reading_data_ = true;
crc_generator_.reset();
goto type2_read_byte;
}
goto type2_read_data;
@@ -571,6 +573,7 @@ void WD1770::posit_event(Event new_event_type)
WAIT_FOR_EVENT(Event::Token);
if(latest_token_.type != Token::Byte) goto type2_read_byte;
data_ = latest_token_.byte_value;
crc_generator_.add(data_);
update_status([] (Status &status) {
status.lost_data |= status.data_request;
status.data_request = true;
@@ -590,7 +593,12 @@ void WD1770::posit_event(Event new_event_type)
distance_into_section_++;
if(distance_into_section_ == 2)
{
// TODO: check CRC
uint16_t crc = crc_generator_.get_value();
if((crc >> 8) != header_[0] || (crc&0xff) != header_[1])
{
printf("CRC error: %04x v %02x%02x\n", crc, header_[0], header_[1]);
}
if(command_ & 0x10)
{
sector_++;
@@ -640,6 +648,7 @@ void WD1770::posit_event(Event new_event_type)
WAIT_FOR_EVENT(Event::DataWritten);
distance_into_section_ = 0;
crc_generator_.reset();
type2_write_loop:
/*
@@ -650,6 +659,7 @@ void WD1770::posit_event(Event new_event_type)
natural expectations and the way that emulated machines responded, I believe that to be a
documentation error.
*/
crc_generator_.add(data_);
write_byte(data_);
distance_into_section_++;
if(distance_into_section_ < 128 << header_[3])
@@ -675,9 +685,11 @@ void WD1770::posit_event(Event new_event_type)
goto type2_write_loop;
type2_write_crc:
// TODO: write CRC
write_byte(0);
write_byte(0);
{
uint16_t crc = crc_generator_.get_value();
write_byte(crc >> 8);
write_byte((crc & 0xff));
}
write_byte(0xff);
WAIT_FOR_EVENT(Event::DataWritten);
end_writing();