render: introduce shared memory allocator

It allocates in local main memory via shm_open, and provides a FD
to allow sharing with other processes.

This is suitable for software rendering under the Wayland and X11
backends.
This commit is contained in:
Simon Ser 2021-02-09 20:57:47 +01:00
parent 6c61de996c
commit c6b009ef85
3 changed files with 132 additions and 0 deletions

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@ -0,0 +1,23 @@
#ifndef RENDER_SHM_ALLOCATOR_H
#define RENDER_SHM_ALLOCATOR_H
#include <wlr/types/wlr_buffer.h>
#include "render/allocator.h"
struct wlr_shm_buffer {
struct wlr_buffer base;
struct wlr_shm_attributes shm;
void *data;
size_t size;
};
struct wlr_shm_allocator {
struct wlr_allocator base;
};
/**
* Creates a new shared memory allocator.
*/
struct wlr_shm_allocator *wlr_shm_allocator_create(void);
#endif

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@ -5,6 +5,7 @@ wlr_files += files(
'drm_format_set.c', 'drm_format_set.c',
'gbm_allocator.c', 'gbm_allocator.c',
'pixel_format.c', 'pixel_format.c',
'shm_allocator.c',
'swapchain.c', 'swapchain.c',
'wlr_renderer.c', 'wlr_renderer.c',
'wlr_texture.c', 'wlr_texture.c',

108
render/shm_allocator.c Normal file
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@ -0,0 +1,108 @@
#include <assert.h>
#include <drm_fourcc.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <unistd.h>
#include <wlr/util/log.h>
#include "render/pixel_format.h"
#include "render/shm_allocator.h"
#include "util/shm.h"
static const struct wlr_buffer_impl buffer_impl;
static struct wlr_shm_buffer *shm_buffer_from_buffer(
struct wlr_buffer *wlr_buffer) {
assert(wlr_buffer->impl == &buffer_impl);
return (struct wlr_shm_buffer *)wlr_buffer;
}
static void buffer_destroy(struct wlr_buffer *wlr_buffer) {
struct wlr_shm_buffer *buffer = shm_buffer_from_buffer(wlr_buffer);
munmap(buffer->data, buffer->size);
close(buffer->shm.fd);
free(buffer);
}
static bool buffer_get_shm(struct wlr_buffer *wlr_buffer,
struct wlr_shm_attributes *shm) {
struct wlr_shm_buffer *buffer = shm_buffer_from_buffer(wlr_buffer);
memcpy(shm, &buffer->shm, sizeof(*shm));
return true;
}
static bool buffer_get_data_ptr(struct wlr_buffer *wlr_buffer, void **data,
size_t *stride) {
struct wlr_shm_buffer *buffer = shm_buffer_from_buffer(wlr_buffer);
*data = buffer->data;
*stride = buffer->shm.stride;
return true;
}
static const struct wlr_buffer_impl buffer_impl = {
.destroy = buffer_destroy,
.get_shm = buffer_get_shm,
.get_data_ptr = buffer_get_data_ptr,
};
static struct wlr_buffer *allocator_create_buffer(
struct wlr_allocator *wlr_allocator, int width, int height,
const struct wlr_drm_format *format) {
const struct wlr_pixel_format_info *info =
drm_get_pixel_format_info(format->format);
if (info == NULL) {
wlr_log(WLR_ERROR, "Unsupported pixel format 0x%"PRIX32, format->format);
return NULL;
}
struct wlr_shm_buffer *buffer = calloc(1, sizeof(*buffer));
if (buffer == NULL) {
return NULL;
}
wlr_buffer_init(&buffer->base, &buffer_impl, width, height);
// TODO: consider using a single file for multiple buffers
int bytes_per_pixel = info->bpp / 8;
int stride = width * bytes_per_pixel; // TODO: align?
buffer->size = stride * height;
buffer->shm.fd = allocate_shm_file(buffer->size);
if (buffer->shm.fd < 0) {
free(buffer);
return NULL;
}
buffer->shm.format = format->format;
buffer->shm.width = width;
buffer->shm.height = height;
buffer->shm.stride = stride;
buffer->shm.offset = 0;
buffer->data = mmap(NULL, buffer->size, PROT_READ | PROT_WRITE, MAP_SHARED,
buffer->shm.fd, 0);
if (buffer->data == MAP_FAILED) {
wlr_log_errno(WLR_ERROR, "mmap failed");
close(buffer->shm.fd);
free(buffer);
return NULL;
}
return &buffer->base;
}
static void allocator_destroy(struct wlr_allocator *wlr_allocator) {
free(wlr_allocator);
}
static const struct wlr_allocator_interface allocator_impl = {
.destroy = allocator_destroy,
.create_buffer = allocator_create_buffer,
};
struct wlr_shm_allocator *wlr_shm_allocator_create(void) {
struct wlr_shm_allocator *allocator = calloc(1, sizeof(*allocator));
if (allocator == NULL) {
return NULL;
}
wlr_allocator_init(&allocator->base, &allocator_impl);
return allocator;
}