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Privatises write_pointers_mutex_ and write_pointers_.

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Also gives subclasses control over write-area texture space allocation.
This commit is contained in:
Thomas Harte 2020-07-23 22:54:40 -04:00
parent 74788ccf8e
commit e260f92988
4 changed files with 63 additions and 45 deletions
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35
Outputs/OpenGL/ScanTarget.cpp
View File

@ -79,10 +79,6 @@ ScanTarget::ScanTarget(GLuint target_framebuffer, float output_gamma) :
unprocessed_line_texture_(LineBufferWidth, LineBufferHeight, UnprocessedLineBufferTextureUnit, GL_NEAREST, false),
full_display_rectangle_(-1.0f, -1.0f, 2.0f, 2.0f) {
// Ensure proper initialisation of the two atomic pointer sets.
read_pointers_.store(write_pointers_);
submit_pointers_.store(write_pointers_);
// Allocate space for the scans and lines.
allocate_buffer(scan_buffer_, scan_buffer_name_, scan_vertex_array_);
allocate_buffer(line_buffer_, line_buffer_name_, line_vertex_array_);
@ -96,8 +92,7 @@ ScanTarget::ScanTarget(GLuint target_framebuffer, float output_gamma) :
test_gl(glBlendFunc, GL_SRC_ALPHA, GL_CONSTANT_COLOR);
test_gl(glBlendColor, 0.4f, 0.4f, 0.4f, 1.0f);
// Establish initial state for the two atomic flags.
is_updating_.clear();
// Establish initial state for is_drawing_to_accumulation_buffer_.
is_drawing_to_accumulation_buffer_.clear();
}
@ -119,17 +114,9 @@ void ScanTarget::setup_pipeline() {
// Ensure the lock guard here has a restricted scope; this is the only time that a thread
// other than the main owner of write_pointers_ may adjust it.
{
std::lock_guard lock_guard(write_pointers_mutex_);
if(data_type_size != data_type_size_) {
// TODO: flush output.
data_type_size_ = data_type_size;
write_area_texture_.resize(WriteAreaWidth*WriteAreaHeight*data_type_size_);
write_pointers_.scan_buffer = 0;
write_pointers_.write_area = 0;
}
if(data_type_size != write_area_data_size()) {
write_area_texture_.resize(WriteAreaWidth*WriteAreaHeight*data_type_size);
set_write_area(write_area_texture_.data());
}
// Prepare to bind line shaders.
@ -252,11 +239,11 @@ void ScanTarget::update(int, int output_height) {
test_gl(glTexImage2D,
GL_TEXTURE_2D,
0,
internalFormatForDepth(data_type_size_),
internalFormatForDepth(write_area_data_size()),
WriteAreaWidth,
WriteAreaHeight,
0,
formatForDepth(data_type_size_),
formatForDepth(write_area_data_size()),
GL_UNSIGNED_BYTE,
nullptr);
texture_exists_ = true;
@ -271,9 +258,9 @@ void ScanTarget::update(int, int output_height) {
0, start_y,
WriteAreaWidth,
1 + end_y - start_y,
formatForDepth(data_type_size_),
formatForDepth(write_area_data_size()),
GL_UNSIGNED_BYTE,
&write_area_texture_[size_t(TextureAddress(0, start_y)) * data_type_size_]);
&write_area_texture_[size_t(TextureAddress(0, start_y)) * write_area_data_size()]);
} else {
// The circular buffer wrapped around; submit the data from the read pointer to the end of
// the buffer and from the start of the buffer to the submit pointer.
@ -282,7 +269,7 @@ void ScanTarget::update(int, int output_height) {
0, 0,
WriteAreaWidth,
1 + end_y,
formatForDepth(data_type_size_),
formatForDepth(write_area_data_size()),
GL_UNSIGNED_BYTE,
&write_area_texture_[0]);
test_gl(glTexSubImage2D,
@ -290,9 +277,9 @@ void ScanTarget::update(int, int output_height) {
0, start_y,
WriteAreaWidth,
WriteAreaHeight - start_y,
formatForDepth(data_type_size_),
formatForDepth(write_area_data_size()),
GL_UNSIGNED_BYTE,
&write_area_texture_[size_t(TextureAddress(0, start_y)) * data_type_size_]);
&write_area_texture_[size_t(TextureAddress(0, start_y)) * write_area_data_size()]);
}
}

3
Outputs/OpenGL/ScanTarget.hpp
View File

@ -145,6 +145,9 @@ class ScanTarget: public Outputs::Display::BufferingScanTarget {
contrast tends to be low, such as a composite colour display.
*/
bool is_soft_display_type();
// Storage for the write area.
std::vector<uint8_t> write_area_texture_;
};
}

36
Outputs/ScanTargets/BufferingScanTarget.cpp
View File

@ -10,6 +10,15 @@
using namespace Outputs::Display;
BufferingScanTarget::BufferingScanTarget() {
// Ensure proper initialisation of the two atomic pointer sets.
read_pointers_.store(write_pointers_);
submit_pointers_.store(write_pointers_);
// Establish initial state for is_updating_.
is_updating_.clear();
}
void BufferingScanTarget::set_modals(Modals modals) {
// Don't change the modals while drawing is ongoing; a previous set might be
// in the process of being established.
@ -47,7 +56,7 @@ uint8_t *BufferingScanTarget::begin_data(size_t required_length, size_t required
if(allocation_has_failed_) return nullptr;
std::lock_guard lock_guard(write_pointers_mutex_);
if(write_area_texture_.empty()) {
if(!write_area_) {
allocation_has_failed_ = true;
return nullptr;
}
@ -84,8 +93,8 @@ uint8_t *BufferingScanTarget::begin_data(size_t required_length, size_t required
data_is_allocated_ = true;
vended_write_area_pointer_ = write_pointers_.write_area = TextureAddress(aligned_start_x, output_y);
assert(write_pointers_.write_area >= 1 && ((size_t(write_pointers_.write_area) + required_length + 1) * data_type_size_) <= write_area_texture_.size());
return &write_area_texture_[size_t(write_pointers_.write_area) * data_type_size_];
assert(write_pointers_.write_area >= 1 && ((size_t(write_pointers_.write_area) + required_length + 1) * data_type_size_) <= WriteAreaWidth*WriteAreaHeight*data_type_size_);
return &write_area_[size_t(write_pointers_.write_area) * data_type_size_];
// Note state at exit:
// write_pointers_.write_area points to the first pixel the client is expected to draw to.
@ -98,8 +107,8 @@ void BufferingScanTarget::end_data(size_t actual_length) {
// Bookend the start of the new data, to safeguard for precision errors in sampling.
memcpy(
&write_area_texture_[size_t(write_pointers_.write_area - 1) * data_type_size_],
&write_area_texture_[size_t(write_pointers_.write_area) * data_type_size_],
&write_area_[size_t(write_pointers_.write_area - 1) * data_type_size_],
&write_area_[size_t(write_pointers_.write_area) * data_type_size_],
data_type_size_);
// Advance to the end of the current run.
@ -107,14 +116,14 @@ void BufferingScanTarget::end_data(size_t actual_length) {
// Also bookend the end.
memcpy(
&write_area_texture_[size_t(write_pointers_.write_area - 1) * data_type_size_],
&write_area_texture_[size_t(write_pointers_.write_area - 2) * data_type_size_],
&write_area_[size_t(write_pointers_.write_area - 1) * data_type_size_],
&write_area_[size_t(write_pointers_.write_area - 2) * data_type_size_],
data_type_size_);
// The write area was allocated in the knowledge that there's sufficient
// distance left on the current line, but there's a risk of exactly filling
// the final line, in which case this should wrap back to 0.
write_pointers_.write_area %= (write_area_texture_.size() / data_type_size_);
write_pointers_.write_area %= WriteAreaWidth*WriteAreaHeight;
// Record that no further end_data calls are expected.
data_is_allocated_ = false;
@ -238,3 +247,14 @@ Outputs::Display::ScanTarget::Scan *BufferingScanTarget::begin_scan() {
vended_scan_ = result;
return &result->scan;
}
void BufferingScanTarget::set_write_area(uint8_t *base) {
std::lock_guard lock_guard(write_pointers_mutex_);
write_area_ = base;
data_type_size_ = Outputs::Display::size_for_data_type(modals_.input_data_type);
write_pointers_ = submit_pointers_ = read_pointers_ = PointerSet();
}
size_t BufferingScanTarget::write_area_data_size() const {
return data_type_size_;
}

34
Outputs/ScanTargets/BufferingScanTarget.hpp
View File

@ -29,7 +29,7 @@ namespace Display {
Provides basic thread-safe (hopefully) circular queues for any scan target that:
* will store incoming Scans into a linear circular buffer and pack regions of
incoming pixel data into a 2d texture;
incoming pixel data into a 2048x2048 2d texture;
* will compose whole lines of content by partioning the Scans based on sync
placement and then pasting together their content;
* will process those lines as necessary to map from input format to whatever
@ -44,6 +44,8 @@ class BufferingScanTarget: public Outputs::Display::ScanTarget {
const Metrics &display_metrics();
protected:
BufferingScanTarget();
// Extends the definition of a Scan to include two extra fields,
// completing this scan's source data and destination locations.
struct Scan {
@ -99,11 +101,6 @@ class BufferingScanTarget: public Outputs::Display::ScanTarget {
// That'll allow owners to place this in shared video memory if possible.
std::array<Scan, 16384> scan_buffer_;
/// A mutex for gettng access to write_pointers_; access to write_pointers_,
/// data_type_size_ or write_area_texture_ is almost never contended, so this
/// is cheap for the main use case.
std::mutex write_pointers_mutex_;
struct PointerSet {
// This constructor is here to appease GCC's interpretation of
// an ambiguity in the C++ standard; cf. https://stackoverflow.com/questions/17430377
@ -116,9 +113,6 @@ class BufferingScanTarget: public Outputs::Display::ScanTarget {
uint16_t line = 0;
};
/// A pointer to the next thing that should be provided to the caller for data.
PointerSet write_pointers_;
/// A pointer to the final thing currently cleared for submission.
std::atomic<PointerSet> submit_pointers_;
@ -144,15 +138,17 @@ class BufferingScanTarget: public Outputs::Display::ScanTarget {
Metrics display_metrics_;
// Uses a texture to vend write areas.
std::vector<uint8_t> write_area_texture_;
size_t data_type_size_ = 0;
bool output_is_visible_ = false;
std::array<Line, LineBufferHeight> line_buffer_;
std::array<LineMetadata, LineBufferHeight> line_metadata_buffer_;
// Used by subclasses to set a new base address for the texture.
// When called this will flush all existing data and load up the
// new data size.
void set_write_area(uint8_t *base);
size_t write_area_data_size() const;
private:
// ScanTarget overrides.
void set_modals(Modals) final;
@ -162,6 +158,18 @@ class BufferingScanTarget: public Outputs::Display::ScanTarget {
void end_data(size_t actual_length) final;
void announce(Event event, bool is_visible, const Outputs::Display::ScanTarget::Scan::EndPoint &location, uint8_t colour_burst_amplitude) final;
void will_change_owner() final;
/// A mutex for gettng access to write_pointers_; access to write_pointers_,
/// data_type_size_ or write_area_texture_ is almost never contended, so this
/// is cheap for the main use case.
std::mutex write_pointers_mutex_;
/// A pointer to the next thing that should be provided to the caller for data.
PointerSet write_pointers_;
// Uses a texture to vend write areas.
uint8_t *write_area_ = nullptr;
size_t data_type_size_ = 0;
};