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Starts the process of supporting the Apple IIe graphics modes.

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Albeit that I'm not yet even up on the proper soft switches.
This commit is contained in:
Thomas Harte 2018-07-23 22:14:41 -04:00
parent 6b2970f2f2
commit 59b9e39022
2 changed files with 84 additions and 2 deletions
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3
Machines/AppleII/AppleII.cpp
View File

@ -62,6 +62,9 @@ class ConcreteMachine:
uint8_t perform_read(uint16_t address) {
return ram_[address];
}
uint16_t perform_aux_read(uint16_t address) {
return static_cast<uint16_t>(ram_[address] | (ram_[address] << 8));
}
private:
uint8_t *ram_;

83
Machines/AppleII/Video.hpp
View File

@ -19,9 +19,21 @@ namespace Video {
class BusHandler {
public:
/*!
Reads an 8-bit value from the ordinary II/II+ memory pool.
*/
uint8_t perform_read(uint16_t address) {
return 0xff;
}
/*!
Reads two 8-bit values, from the same address — one from
main RAM, one from auxiliary. Should return as
(main) | (aux << 8).
*/
uint16_t perform_aux_read(uint16_t address) {
return 0xffff;
}
};
class VideoBase {
@ -55,8 +67,11 @@ class VideoBase {
enum class GraphicsMode {
LowRes,
DoubleLowRes,
HighRes,
Text
DoubleHighRes,
Text,
DoubleText
} graphics_mode_ = GraphicsMode::LowRes;
bool use_graphics_mode_ = false;
bool mixed_mode_ = false;
@ -153,11 +168,51 @@ template <class BusHandler> class Video: public VideoBase {
pixel_pointer_[4] = character_pattern & 0x04;
pixel_pointer_[5] = character_pattern & 0x02;
pixel_pointer_[6] = character_pattern & 0x01;
graphics_carry_ = character_pattern & 0x40;
graphics_carry_ = character_pattern & 0x01;
pixel_pointer_ += 7;
}
} break;
case GraphicsMode::DoubleText: {
const uint8_t inverses[] = {
0xff,
static_cast<uint8_t>((flash_ / flash_length) * 0xff),
0x00,
0x00
};
for(int c = column_; c < pixel_end; ++c) {
const uint16_t characters = bus_handler_.perform_aux_read(static_cast<uint16_t>(text_address + c));
const std::size_t character_addresses[2] = {
static_cast<std::size_t>(((characters & 0x3f) << 3) + pixel_row),
static_cast<std::size_t>((((characters >> 8) & 0x3f) << 3) + pixel_row),
};
const uint8_t character_patterns[2] = {
static_cast<uint8_t>(character_rom_[character_addresses[0]] ^ inverses[(characters >> 6) & 3]),
static_cast<uint8_t>(character_rom_[character_addresses[1]] ^ inverses[(characters >> 14) & 3]),
};
// The character ROM is output MSB to LSB rather than LSB to MSB.
pixel_pointer_[0] = character_patterns[0] & 0x40;
pixel_pointer_[1] = character_patterns[0] & 0x20;
pixel_pointer_[2] = character_patterns[0] & 0x10;
pixel_pointer_[3] = character_patterns[0] & 0x08;
pixel_pointer_[4] = character_patterns[0] & 0x04;
pixel_pointer_[5] = character_patterns[0] & 0x02;
pixel_pointer_[6] = character_patterns[0] & 0x01;
pixel_pointer_[7] = character_patterns[1] & 0x40;
pixel_pointer_[8] = character_patterns[1] & 0x20;
pixel_pointer_[9] = character_patterns[1] & 0x10;
pixel_pointer_[10] = character_patterns[1] & 0x08;
pixel_pointer_[11] = character_patterns[1] & 0x04;
pixel_pointer_[12] = character_patterns[1] & 0x02;
pixel_pointer_[13] = character_patterns[1] & 0x01;
graphics_carry_ = character_patterns[1] & 0x01;
pixel_pointer_ += 14;
}
} break;
case GraphicsMode::DoubleLowRes:
case GraphicsMode::LowRes: {
const int row_shift = (row_&4);
// TODO: decompose into two loops, possibly.
@ -212,6 +267,30 @@ template <class BusHandler> class Video: public VideoBase {
pixel_pointer_ += 14;
}
} break;
case GraphicsMode::DoubleHighRes: {
const uint16_t graphics_address = static_cast<uint16_t>(((video_page_+1) * 0x2000) + row_address + ((pixel_row&7) << 10));
for(int c = column_; c < pixel_end; ++c) {
const uint16_t graphic = bus_handler_.perform_aux_read(static_cast<uint16_t>(graphics_address + c));
pixel_pointer_[0] = graphic & 0x01;
pixel_pointer_[1] = graphic & 0x02;
pixel_pointer_[2] = graphic & 0x04;
pixel_pointer_[3] = graphic & 0x08;
pixel_pointer_[4] = graphic & 0x10;
pixel_pointer_[5] = graphic & 0x20;
pixel_pointer_[6] = graphic & 0x40;
pixel_pointer_[7] = (graphic >> 8) & 0x01;
pixel_pointer_[8] = (graphic >> 8) & 0x02;
pixel_pointer_[9] = (graphic >> 8) & 0x04;
pixel_pointer_[10] = (graphic >> 8) & 0x08;
pixel_pointer_[11] = (graphic >> 8) & 0x10;
pixel_pointer_[12] = (graphic >> 8) & 0x20;
pixel_pointer_[13] = (graphic >> 8) & 0x40;
graphics_carry_ = (graphic >> 8) & 0x40;
pixel_pointer_ += 14;
}
} break;
}
if(ending_column >= 40) {