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Breaks up loop for arithmetic simplicity.

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This commit is contained in:
Thomas Harte 2021-07-27 21:59:27 -04:00
parent 402eab10f8
commit 82205d71cc
2 changed files with 48 additions and 44 deletions
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71
Machines/Amiga/Chipset.cpp
View File

@ -127,6 +127,8 @@ bool Chipset::Copper::advance(uint16_t position) {
}
template <int cycle> void Chipset::output() {
// Notes to self on guesses below:
//
// Hardware stop is at 0x18;
// 12/64 * 227 = 42.5625
//
@ -242,53 +244,26 @@ template <int cycle, bool stop_if_cpu> bool Chipset::perform_cycle() {
return false;
}
template <bool stop_on_cpu> Chipset::Changes Chipset::run(HalfCycles length) {
Changes changes;
// This code uses 'pixels' as a measure, which is equivalent to one pixel clock time,
// or half a cycle.
auto pixels_remaining = length.as<int>();
// Update raster position, spooling out graphics.
while(pixels_remaining) {
// Determine number of pixels left on this line.
int line_pixels = std::min(pixels_remaining, (line_length_ * 4) - line_cycle_);
//
// Run DMA scheduler.
//
int final_slot = (line_cycle_ + line_pixels) >> 2;
if((line_cycle_ >> 2) == final_slot) {
// Not enough pixels left to fill any whole slots, just stop.
line_cycle_ += line_pixels;
break;
template <bool stop_on_cpu> int Chipset::advance_slots(int first_slot, int last_slot) {
if(first_slot == last_slot) {
return -1;
}
// Advance to window boundary.
const int distance_to_boundary = ((line_cycle_ - 1) & 3) ^ 3;
line_pixels -= distance_to_boundary;
pixels_remaining -= distance_to_boundary;
line_cycle_ += distance_to_boundary;
#define C(x) \
case x: \
assert(!(line_cycle_&3)); \
if constexpr(stop_on_cpu) {\
if(perform_cycle<x, stop_on_cpu>()) {\
break;\
return x - first_slot;\
}\
} else {\
perform_cycle<x, stop_on_cpu>(); \
} \
output<x>(); \
if((line_cycle_ >> 2) == final_slot) break; \
line_cycle_ += 4; \
pixels_remaining -= 4;
if((x + 1) == last_slot) break; \
[[fallthrough]]
#define C10(x) C(x); C(x+1); C(x+2); C(x+3); C(x+4); C(x+5); C(x+6); C(x+7); C(x+8); C(x+9);
switch(line_cycle_ >> 2) {
switch(first_slot) {
C10(0); C10(10); C10(20); C10(30); C10(40);
C10(50); C10(60); C10(70); C10(80); C10(90);
C10(100); C10(110); C10(120); C10(130); C10(140);
@ -301,6 +276,33 @@ template <bool stop_on_cpu> Chipset::Changes Chipset::run(HalfCycles length) {
}
#undef C
return -1;
}
template <bool stop_on_cpu> Chipset::Changes Chipset::run(HalfCycles length) {
Changes changes;
// This code uses 'pixels' as a measure, which is equivalent to one pixel clock time,
// or half a cycle.
auto pixels_remaining = length.as<int>();
// Update raster position, spooling out graphics.
while(pixels_remaining) {
// Determine number of pixels left on this line.
const int line_pixels = std::min(pixels_remaining, (line_length_ * 4) - line_cycle_);
const int start_slot = line_cycle_ >> 2;
const int end_slot = (line_cycle_ + line_pixels) >> 2;
const int actual_slots = advance_slots<stop_on_cpu>(start_slot, end_slot);
if(actual_slots >= 0) {
// TODO: abbreviate run, prior to adding to totals below.
assert(false);
}
line_cycle_ += line_pixels;
pixels_remaining -= line_pixels;
// Advance intraline counter and possibly ripple upwards into
// lines and fields.
if(line_cycle_ == (line_length_ * 4)) {
@ -320,6 +322,7 @@ template <bool stop_on_cpu> Chipset::Changes Chipset::run(HalfCycles length) {
copper_.reload(0);
}
}
assert(line_cycle_ < line_length_ * 4);
}
changes.interrupt_level = interrupt_level_;

1
Machines/Amiga/Chipset.hpp
View File

@ -66,6 +66,7 @@ class Chipset {
// MARK: - Scheduler.
template <bool stop_on_cpu> Changes run(HalfCycles duration = HalfCycles());
template <bool stop_on_cpu> int advance_slots(int, int);
template <int cycle, bool stop_if_cpu> bool perform_cycle();
template <int cycle> void output();