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Takes a stab at double low-res graphics.

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This commit is contained in:
Thomas Harte 2018-07-31 21:45:09 -04:00
parent a36f37d240
commit c91eaaf8da
1 changed files with 33 additions and 2 deletions
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35
Machines/AppleII/Video.hpp
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@ -159,7 +159,7 @@ class VideoBase {
// State affecting logical state.
int row_ = 0, column_ = 0, flash_ = 0;
// An
// Enumerates all Apple II and IIe display modes.
enum class GraphicsMode {
LowRes,
DoubleLowRes,
@ -324,7 +324,38 @@ template <class BusHandler> class Video: public VideoBase {
}
} break;
case GraphicsMode::DoubleLowRes:
case GraphicsMode::DoubleLowRes: {
const int row_shift = (row_&4);
for(int c = column_; c < pixel_end; ++c) {
const uint16_t nibble = (bus_handler_.perform_aux_read(static_cast<uint16_t>(text_address + c)) >> row_shift) & 0xf0f;
if(c&1) {
pixel_pointer_[0] = pixel_pointer_[4] = (nibble >> 8) & 4;
pixel_pointer_[1] = pixel_pointer_[5] = (nibble >> 8) & 8;
pixel_pointer_[2] = pixel_pointer_[6] = (nibble >> 8) & 1;
pixel_pointer_[3] = (nibble >> 8) & 2;
pixel_pointer_[8] = pixel_pointer_[12] = nibble & 4;
pixel_pointer_[9] = pixel_pointer_[13] = nibble & 8;
pixel_pointer_[10] = nibble & 1;
pixel_pointer_[7] = pixel_pointer_[11] = nibble & 2;
graphics_carry_ = nibble & 8;
} else {
pixel_pointer_[0] = pixel_pointer_[4] = (nibble >> 8) & 1;
pixel_pointer_[1] = pixel_pointer_[5] = (nibble >> 8) & 2;
pixel_pointer_[2] = pixel_pointer_[6] = (nibble >> 8) & 4;
pixel_pointer_[3] = (nibble >> 8) & 8;
pixel_pointer_[8] = pixel_pointer_[12] = nibble & 1;
pixel_pointer_[9] = pixel_pointer_[13] = nibble & 2;
pixel_pointer_[10] = nibble & 4;
pixel_pointer_[7] = pixel_pointer_[11] = nibble & 8;
graphics_carry_ = nibble & 2;
}
pixel_pointer_ += 14;
}
} break;
case GraphicsMode::LowRes: {
const int row_shift = (row_&4);
// TODO: decompose into two loops, possibly.