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Merge pull request #1073 from TomHarte/AmigaSprites

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Improve Amiga sprite emulation.
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Thomas Harte 2022-07-20 13:53:50 -04:00 committed by GitHub
commit b67790df7d
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3 changed files with 59 additions and 56 deletions
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33
Machines/Amiga/Chipset.cpp
View File

@ -21,6 +21,8 @@
using namespace Amiga;
// TODO: I don't think the nonsense below, which was intended to allow a typed enum but also
// clean combination, really works. Rethink.
namespace {
template <typename EnumT, EnumT... T> struct Mask {
@ -34,6 +36,18 @@ template <typename EnumT, EnumT F, EnumT... T> struct Mask<EnumT, F, T...> {
template <InterruptFlag... Flags> struct InterruptMask: Mask<InterruptFlag, Flags...> {};
template <DMAFlag... Flags> struct DMAMask: Mask<DMAFlag, Flags...> {};
constexpr uint16_t AudioFlags[] = {
DMAMask<DMAFlag::AudioChannel0, DMAFlag::AllBelow>::value,
DMAMask<DMAFlag::AudioChannel1, DMAFlag::AllBelow>::value,
DMAMask<DMAFlag::AudioChannel2, DMAFlag::AllBelow>::value,
DMAMask<DMAFlag::AudioChannel3, DMAFlag::AllBelow>::value,
};
constexpr auto BlitterFlag = DMAMask<DMAFlag::Blitter, DMAFlag::AllBelow>::value;
constexpr auto BitplaneFlag = DMAMask<DMAFlag::Bitplane, DMAFlag::AllBelow>::value;
constexpr auto CopperFlag = DMAMask<DMAFlag::Copper, DMAFlag::AllBelow>::value;
constexpr auto DiskFlag = DMAMask<DMAFlag::Disk, DMAFlag::AllBelow>::value;
constexpr auto SpritesFlag = DMAMask<DMAFlag::Sprites, DMAFlag::AllBelow>::value;
}
#define DMA_CONSTRUCT *this, reinterpret_cast<uint16_t *>(map.chip_ram.data()), map.chip_ram.size() >> 1
@ -488,17 +502,6 @@ void Chipset::flush_output() {
/// @returns @c true if this was a CPU slot; @c false otherwise.
template <int cycle, bool stop_if_cpu> bool Chipset::perform_cycle() {
constexpr uint16_t AudioFlags[] = {
DMAMask<DMAFlag::AudioChannel0, DMAFlag::AllBelow>::value,
DMAMask<DMAFlag::AudioChannel1, DMAFlag::AllBelow>::value,
DMAMask<DMAFlag::AudioChannel2, DMAFlag::AllBelow>::value,
DMAMask<DMAFlag::AudioChannel3, DMAFlag::AllBelow>::value,
};
constexpr auto BlitterFlag = DMAMask<DMAFlag::Blitter, DMAFlag::AllBelow>::value;
constexpr auto BitplaneFlag = DMAMask<DMAFlag::Bitplane, DMAFlag::AllBelow>::value;
constexpr auto CopperFlag = DMAMask<DMAFlag::Copper, DMAFlag::AllBelow>::value;
constexpr auto DiskFlag = DMAMask<DMAFlag::Disk, DMAFlag::AllBelow>::value;
constexpr auto SpritesFlag = DMAMask<DMAFlag::Sprites, DMAFlag::AllBelow>::value;
// Update state as to whether bitplane fetching should happen now.
//
@ -607,11 +610,11 @@ template <int cycle, bool stop_if_cpu> bool Chipset::perform_cycle() {
}
if constexpr (cycle >= 0x16 && cycle < 0x36) {
if((dma_control_ & SpritesFlag) == SpritesFlag && y_ >= vertical_blank_height_) {
if((dma_control_ & SpritesFlag) == SpritesFlag) {
constexpr auto sprite_id = (cycle - 0x16) >> 2;
static_assert(sprite_id >= 0 && sprite_id < std::tuple_size<decltype(sprites_)>::value);
if(sprites_[sprite_id].advance_dma(!(cycle&2))) {
if(sprites_[sprite_id].advance_dma((~cycle&2) >> 1, y_, y_ == vertical_blank_height_)) {
return false;
}
}
@ -741,10 +744,6 @@ template <bool stop_on_cpu> Chipset::Changes Chipset::run(HalfCycles length) {
is_long_field_ ^= interlace_;
}
for(auto &sprite: sprites_) {
sprite.advance_line(y_, y_ == vertical_blank_height_);
}
fetch_vertical_ |= y_ == display_window_start_[1];
fetch_vertical_ &= y_ != display_window_stop_[1];
}

74
Machines/Amiga/Sprites.cpp
View File

@ -8,6 +8,8 @@
#include "Sprites.hpp"
#include <cassert>
using namespace Amiga;
namespace {
@ -33,61 +35,69 @@ static_assert(expand_sprite_word(0x0000) == 0x00'00'00'00'00'00'00'00);
// MARK: - Sprites.
void Sprite::set_start_position(uint16_t value) {
// b8–b15: low 8 bits of VSTART;
// b0–b7: high 8 bits of HSTART.
v_start_ = (v_start_ & 0xff00) | (value >> 8);
h_start = uint16_t((h_start & 0x0001) | ((value & 0xff) << 1));
}
void Sprite::set_stop_and_control(uint16_t value) {
// b8–b15: low 8 bits of VSTOP;
// b7: attachment flag;
// b3–b6: unused;
// b2: VSTART high bit;
// b1: VSTOP high bit;
// b0: HSTART low bit.
h_start = uint16_t((h_start & 0x01fe) | (value & 0x01));
v_stop_ = uint16_t((value >> 8) | ((value & 0x02) << 7));
v_start_ = uint16_t((v_start_ & 0x00ff) | ((value & 0x04) << 6));
attached = value & 0x80;
// Disarm the sprite, but expect graphics next from DMA.
// Disarm the sprite.
visible = false;
dma_state_ = DMAState::FetchImage;
}
void Sprite::set_image_data(int slot, uint16_t value) {
// Store data; also mark sprite as visible (i.e. 'arm' it)
// if data is being stored to slot 0.
data[slot] = value;
visible |= slot == 0;
}
void Sprite::advance_line(int y, bool is_end_of_blank) {
if(dma_state_ == DMAState::FetchImage && y == v_start_) {
visible = true;
}
if(is_end_of_blank || y == v_stop_) {
dma_state_ = DMAState::FetchControl;
visible = true;
}
}
bool Sprite::advance_dma(int offset, int y, bool is_first_line) {
assert(offset == 0 || offset == 1);
bool Sprite::advance_dma(int offset) {
if(!visible) return false;
// Fetch another word.
// Determine which word would be fetched, if DMA occurs.
// A bit of a cheat.
const uint16_t next_word = ram_[pointer_[0] & ram_mask_];
++pointer_[0];
// Put the fetched word somewhere appropriate and update the DMA state.
switch(dma_state_) {
// i.e. stopped.
default: return false;
// "When the vertical position of the beam counter is equal to the VSTOP
// value in the sprite control words, the next two words fetched from the
// sprite data structure are written into the sprite control registers
// instead of being sent to the color registers"
//
// Guesswork, primarily from observing Spindizzy Worlds: the first line after
// vertical blank also triggers a control reload. Seek to verify.
if(y == v_stop_ || is_first_line) {
if(offset) {
// Second control word: stop position (mostly).
set_stop_and_control(next_word);
} else {
// First control word: start position.
set_start_position(next_word);
}
} else {
visible |= y == v_start_;
if(!visible) return false; // Act as if there wasn't a fetch.
case DMAState::FetchControl:
if(offset) {
set_stop_and_control(next_word);
} else {
set_start_position(next_word);
}
return true;
case DMAState::FetchImage:
set_image_data(1 - bool(offset), next_word);
return true;
// Write colour word 1, then colour word 0; 0 is the word that 'arms'
// the sprite (i.e. makes it visible).
set_image_data(1 - offset, next_word);
}
return false;
// Acknowledge the fetch.
++pointer_[0];
return true;
}
template <int sprite> void TwoSpriteShifter::load(

8
Machines/Amiga/Sprites.hpp
View File

@ -23,8 +23,7 @@ class Sprite: public DMADevice<1> {
void set_stop_and_control(uint16_t value);
void set_image_data(int slot, uint16_t value);
void advance_line(int y, bool is_end_of_blank);
bool advance_dma(int offset);
bool advance_dma(int offset, int y, bool is_first_line);
uint16_t data[2]{};
bool attached = false;
@ -33,11 +32,6 @@ class Sprite: public DMADevice<1> {
private:
uint16_t v_start_ = 0, v_stop_ = 0;
enum class DMAState {
FetchControl,
FetchImage
} dma_state_ = DMAState::FetchControl;
};
class TwoSpriteShifter {