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Sought to flesh out error conditions.

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This commit is contained in:
Thomas Harte 2017-08-12 16:36:37 -04:00
parent 4909325e79
commit 7135259cc1
1 changed files with 46 additions and 16 deletions
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62
Components/8272/i8272.cpp
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@ -300,16 +300,31 @@ void i8272::posit_event(int event_type) {
index_hole_limit_ = 2;
find_next_sector:
FIND_HEADER();
if(!index_hole_limit_) goto read_data_not_found;
if(!index_hole_limit_) {
// Two index holes have passed wihout finding the header sought.
status_[1] |= 0x4;
goto abort_read;
}
READ_HEADER();
if(get_crc_generator().get_value()) {
// This implies a CRC error in the header; mark as such but continue.
status_[1] |= 0x20;
}
if(header_[0] != cylinder_ || header_[1] != head_ || header_[2] != sector_ || header_[3] != size_) goto find_next_sector;
// Finds the next data block and sets data mode to reading, setting an error flag if the on-disk deleted
// flag doesn't match the sort the command was looking for.
FIND_DATA();
distance_into_section_ = 0;
if((get_latest_token().type == Token::Data) != ((command_[0]&0xf) != 0x6))
status_[2] |= 0x40;
if((get_latest_token().type == Token::Data) != ((command_[0]&0xf) == 0x6)) {
if(!(command_[0]&0x20)) {
// SK is not set; set the error flag but read this sector before finishing.
status_[2] |= 0x40;
} else {
// SK is set; skip this sector.
goto read_next_data;
}
}
set_data_mode(Reading);
// Waits for the next token, then supplies it to the CPU by: (i) setting data request and direction; and (ii) resetting
@ -322,16 +337,33 @@ void i8272::posit_event(int event_type) {
result_stack_.push_back(get_latest_token().byte_value);
distance_into_section_++;
main_status_ |= StatusRequest | StatusDirection;
WAIT_FOR_EVENT(Event8272::ResultEmpty);
main_status_ &= ~StatusRequest;
if(distance_into_section_ < (128 << size_)) goto get_byte;
WAIT_FOR_EVENT((int)Event8272::ResultEmpty | (int)Event::Token | (int)Event::IndexHole);
switch(event_type) {
case (int)Event8272::ResultEmpty: // The caller read the byte in time; proceed as normal.
main_status_ &= ~StatusRequest;
if(distance_into_section_ < (128 << size_)) goto get_byte;
break;
case (int)Event::Token: // The caller hasn't read the old byte yet and a new one has arrived
status_[0] |= 0x10;
goto abort_read;
break;
case (int)Event::IndexHole:
break;
}
// read CRC, without transferring it
// read CRC, without transferring it, then check it
WAIT_FOR_EVENT(Event::Token);
WAIT_FOR_EVENT(Event::Token);
if(get_crc_generator().get_value()) {
// This implies a CRC error in the sector; mark as such and temrinate.
status_[1] |= 0x20;
status_[2] |= 0x20;
goto abort_read;
}
// check whether that's it
if(sector_ != command_[6]) {
// check whether that's it: either the final requested sector has been read, or because
// a sector that was [/wasn't] marked as deleted when it shouldn't [/should] have been
if(sector_ != command_[6] && !(status_[2]&0x40)) {
sector_++;
goto read_next_data;
}
@ -339,12 +371,7 @@ void i8272::posit_event(int event_type) {
// For a final result phase, post the standard ST0, ST1, ST2, C, H, R, N
goto post_st012chrn;
// Execution reaches here if two index holes were discovered before a matching sector — i.e. the data wasn't found.
// In that case set appropriate error flags and post the results.
read_data_not_found:
printf("Not found\n");
status_[1] |= 0x4;
abort_read:
status_[0] = 0x40;
goto post_st012chrn;
@ -372,7 +399,10 @@ void i8272::posit_event(int event_type) {
index_hole_limit_ = 2;
read_id_find_next_sector:
FIND_HEADER();
if(!index_hole_limit_) goto read_data_not_found;
if(!index_hole_limit_) {
status_[1] |= 0x4;
goto abort_read;
}
READ_HEADER();
// Sets internal registers from the discovered header and posts the standard ST0, ST1, ST2, C, H, R, N.