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Merge pull request #196 from TomHarte/Minor6845

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Corrects 8272 multi-sector reads and deleted data reads, and ensures that a zero-height 6845 display shows nothing
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Thomas Harte 2017-08-14 22:31:24 -04:00 committed by GitHub
commit 0972f19fc5
2 changed files with 15 additions and 8 deletions
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2
Components/6845/CRTC6845.hpp
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@ -137,7 +137,7 @@ template <class T> class CRTC6845 {
}
character_counter_ = 0;
character_is_visible_ = true;
character_is_visible_ = (registers_[1] != 0);
}
perform_bus_cycle();

21
Components/8272/i8272.cpp
View File

@ -243,12 +243,18 @@ void i8272::posit_event(int event_type) {
static const size_t required_lengths[32] = {
0, 0, 9, 3, 2, 9, 9, 2,
1, 9, 2, 9, 0, 6, 0, 3,
1, 9, 2, 0, 9, 6, 0, 3,
0, 9, 0, 0, 0, 0, 0, 0,
0, 9, 0, 0, 0, 9, 0, 0,
};
if(command_.size() < required_lengths[command_[0] & 0x1f]) goto wait_for_complete_command_sequence;
if(command_.size() == 9) {
cylinder_ = command_[2];
head_ = command_[3];
sector_ = command_[4];
size_ = command_[5];
}
ResetDataRequest();
status_[0] = status_[1] = status_[2] = 0;
@ -274,7 +280,7 @@ void i8272::posit_event(int event_type) {
// Jump to the proper place.
switch(command_[0] & 0x1f) {
case 0x06: // read data
case 0x0b: // read deleted data
case 0x0c: // read deleted data
goto read_data;
case 0x05: // write data
@ -303,19 +309,18 @@ void i8272::posit_event(int event_type) {
// Establishes the drive and head being addressed, and whether in double density mode; populates the internal
// cylinder, head, sector and size registers from the command stream.
LOAD_HEAD();
cylinder_ = command_[2];
head_ = command_[3];
sector_ = command_[4];
size_ = command_[5];
// Sets a maximum index hole limit of 2 then performs a find header/read header loop, continuing either until
// the index hole limit is breached or a sector is found with a cylinder, head, sector and size equal to the
// values in the internal registers.
index_hole_limit_ = 2;
set_data_mode(DataMode::Scanning);
// printf("Seeking %02x %02x %02x %02x\n", cylinder_, head_, sector_, size_);
find_next_sector:
FIND_HEADER();
if(!index_hole_limit_) {
// Two index holes have passed wihout finding the header sought.
// printf("Not found\n");
SetNoData();
goto abort_read_write;
}
@ -324,12 +329,14 @@ void i8272::posit_event(int event_type) {
// This implies a CRC error in the header; mark as such but continue.
SetDataError();
}
// printf("Considering %02x %02x %02x %02x\n", header_[0], header_[1], header_[2], header_[3]);
if(header_[0] != cylinder_ || header_[1] != head_ || header_[2] != sector_ || header_[3] != size_) goto find_next_sector;
// Branch to whatever is supposed to happen next
// printf("Proceeding\n");
switch(command_[0] & 0x1f) {
case 0x06: // read data
case 0x0b: // read deleted data
case 0x0c: // read deleted data
goto read_data_found_header;
case 0x05: // write data