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Further reduces lines to one access per slot, max.

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This commit is contained in:
Thomas Harte 2022-08-07 19:19:00 -04:00
parent 867769f6e7
commit d4b7d73fc4
2 changed files with 20 additions and 3 deletions
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22
Machines/Amiga/Blitter.cpp
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@ -292,18 +292,30 @@ bool Blitter<record_bus>::advance_dma() {
// at https://github.com/niklasekstrom/blitter-subpixel-line/blob/master/Drawing%20lines%20using%20the%20Amiga%20blitter.pdf
//
//
// Caveat: I've no idea how the DMA access slots should be laid out for
// line drawing.
//
if(!busy_) {
error_ = int16_t(pointer_[0] << 1) >> 1; // TODO: what happens if line_sign_ doesn't agree with this?
draw_ = true;
busy_ = true;
has_c_data_ = false;
}
bool did_output = false;
if(draw_) {
// TODO: patterned lines. Unclear what to do with the bit that comes out of b.
// Probably extend it to a full word?
c_data_ = ram_[pointer_[3] & ram_mask_];
if constexpr (record_bus) {
transactions_.emplace_back(Transaction::Type::ReadC, pointer_[3], c_data_);
if(!has_c_data_) {
has_c_data_ = true;
c_data_ = ram_[pointer_[3] & ram_mask_];
if constexpr (record_bus) {
transactions_.emplace_back(Transaction::Type::ReadC, pointer_[3], c_data_);
}
return true;
}
const uint16_t output =
@ -311,6 +323,8 @@ bool Blitter<record_bus>::advance_dma() {
ram_[pointer_[3] & ram_mask_] = output;
not_zero_flag_ |= output;
draw_ &= !one_dot_;
has_c_data_ = false;
did_output = true;
if constexpr (record_bus) {
transactions_.emplace_back(Transaction::Type::WriteFromPipeline, pointer_[3], output);
}
@ -361,6 +375,8 @@ bool Blitter<record_bus>::advance_dma() {
busy_ = false;
posit_interrupt(InterruptFlag::Blitter);
}
return did_output;
} else {
// Copy mode.
if(!busy_) {

1
Machines/Amiga/Blitter.hpp
View File

@ -263,6 +263,7 @@ template <bool record_bus = false> class Blitter: public DMADevice<4, 4> {
int error_ = 0;
bool draw_ = false;
bool has_c_data_ = false;
void add_modulos();
std::vector<Transaction> transactions_;