SDL_dataqueue.c
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/*
Simple DirectMedia Layer
Copyright (C) 1997-2018 Sam Lantinga <slouken@libsdl.org>
This software is provided 'as-is', without any express or implied
warranty. In no event will the authors be held liable for any damages
arising from the use of this software.
Permission is granted to anyone to use this software for any purpose,
including commercial applications, and to alter it and redistribute it
freely, subject to the following restrictions:
1. The origin of this software must not be misrepresented; you must not
claim that you wrote the original software. If you use this software
in a product, an acknowledgment in the product documentation would be
appreciated but is not required.
2. Altered source versions must be plainly marked as such, and must not be
misrepresented as being the original software.
3. This notice may not be removed or altered from any source distribution.
*/
#include "./SDL_internal.h"
#include "SDL.h"
#include "./SDL_dataqueue.h"
#include "SDL_assert.h"
typedef struct SDL_DataQueuePacket
{
size_t datalen; /* bytes currently in use in this packet. */
size_t startpos; /* bytes currently consumed in this packet. */
struct SDL_DataQueuePacket *next; /* next item in linked list. */
Uint8 data[SDL_VARIABLE_LENGTH_ARRAY]; /* packet data */
} SDL_DataQueuePacket;
struct SDL_DataQueue
{
SDL_DataQueuePacket *head; /* device fed from here. */
SDL_DataQueuePacket *tail; /* queue fills to here. */
SDL_DataQueuePacket *pool; /* these are unused packets. */
size_t packet_size; /* size of new packets */
size_t queued_bytes; /* number of bytes of data in the queue. */
};
static void
SDL_FreeDataQueueList(SDL_DataQueuePacket *packet)
{
while (packet) {
SDL_DataQueuePacket *next = packet->next;
SDL_free(packet);
packet = next;
}
}
/* this all expects that you managed thread safety elsewhere. */
SDL_DataQueue *
SDL_NewDataQueue(const size_t _packetlen, const size_t initialslack)
{
SDL_DataQueue *queue = (SDL_DataQueue *) SDL_malloc(sizeof (SDL_DataQueue));
if (!queue) {
SDL_OutOfMemory();
return NULL;
} else {
const size_t packetlen = _packetlen ? _packetlen : 1024;
const size_t wantpackets = (initialslack + (packetlen - 1)) / packetlen;
size_t i;
SDL_zerop(queue);
queue->packet_size = packetlen;
for (i = 0; i < wantpackets; i++) {
SDL_DataQueuePacket *packet = (SDL_DataQueuePacket *) SDL_malloc(sizeof (SDL_DataQueuePacket) + packetlen);
if (packet) { /* don't care if this fails, we'll deal later. */
packet->datalen = 0;
packet->startpos = 0;
packet->next = queue->pool;
queue->pool = packet;
}
}
}
return queue;
}
void
SDL_FreeDataQueue(SDL_DataQueue *queue)
{
if (queue) {
SDL_FreeDataQueueList(queue->head);
SDL_FreeDataQueueList(queue->pool);
SDL_free(queue);
}
}
void
SDL_ClearDataQueue(SDL_DataQueue *queue, const size_t slack)
{
const size_t packet_size = queue ? queue->packet_size : 1;
const size_t slackpackets = (slack + (packet_size-1)) / packet_size;
SDL_DataQueuePacket *packet;
SDL_DataQueuePacket *prev = NULL;
size_t i;
if (!queue) {
return;
}
packet = queue->head;
/* merge the available pool and the current queue into one list. */
if (packet) {
queue->tail->next = queue->pool;
} else {
packet = queue->pool;
}
/* Remove the queued packets from the device. */
queue->tail = NULL;
queue->head = NULL;
queue->queued_bytes = 0;
queue->pool = packet;
/* Optionally keep some slack in the pool to reduce malloc pressure. */
for (i = 0; packet && (i < slackpackets); i++) {
prev = packet;
packet = packet->next;
}
if (prev) {
prev->next = NULL;
} else {
queue->pool = NULL;
}
SDL_FreeDataQueueList(packet); /* free extra packets */
}
static SDL_DataQueuePacket *
AllocateDataQueuePacket(SDL_DataQueue *queue)
{
SDL_DataQueuePacket *packet;
SDL_assert(queue != NULL);
packet = queue->pool;
if (packet != NULL) {
/* we have one available in the pool. */
queue->pool = packet->next;
} else {
/* Have to allocate a new one! */
packet = (SDL_DataQueuePacket *) SDL_malloc(sizeof (SDL_DataQueuePacket) + queue->packet_size);
if (packet == NULL) {
return NULL;
}
}
packet->datalen = 0;
packet->startpos = 0;
packet->next = NULL;
SDL_assert((queue->head != NULL) == (queue->queued_bytes != 0));
if (queue->tail == NULL) {
queue->head = packet;
} else {
queue->tail->next = packet;
}
queue->tail = packet;
return packet;
}
int
SDL_WriteToDataQueue(SDL_DataQueue *queue, const void *_data, const size_t _len)
{
size_t len = _len;
const Uint8 *data = (const Uint8 *) _data;
const size_t packet_size = queue ? queue->packet_size : 0;
SDL_DataQueuePacket *orighead;
SDL_DataQueuePacket *origtail;
size_t origlen;
size_t datalen;
if (!queue) {
return SDL_InvalidParamError("queue");
}
orighead = queue->head;
origtail = queue->tail;
origlen = origtail ? origtail->datalen : 0;
while (len > 0) {
SDL_DataQueuePacket *packet = queue->tail;
SDL_assert(!packet || (packet->datalen <= packet_size));
if (!packet || (packet->datalen >= packet_size)) {
/* tail packet missing or completely full; we need a new packet. */
packet = AllocateDataQueuePacket(queue);
if (!packet) {
/* uhoh, reset so we've queued nothing new, free what we can. */
if (!origtail) {
packet = queue->head; /* whole queue. */
} else {
packet = origtail->next; /* what we added to existing queue. */
origtail->next = NULL;
origtail->datalen = origlen;
}
queue->head = orighead;
queue->tail = origtail;
queue->pool = NULL;
SDL_FreeDataQueueList(packet); /* give back what we can. */
return SDL_OutOfMemory();
}
}
datalen = SDL_min(len, packet_size - packet->datalen);
SDL_memcpy(packet->data + packet->datalen, data, datalen);
data += datalen;
len -= datalen;
packet->datalen += datalen;
queue->queued_bytes += datalen;
}
return 0;
}
size_t
SDL_PeekIntoDataQueue(SDL_DataQueue *queue, void *_buf, const size_t _len)
{
size_t len = _len;
Uint8 *buf = (Uint8 *) _buf;
Uint8 *ptr = buf;
SDL_DataQueuePacket *packet;
if (!queue) {
return 0;
}
for (packet = queue->head; len && packet; packet = packet->next) {
const size_t avail = packet->datalen - packet->startpos;
const size_t cpy = SDL_min(len, avail);
SDL_assert(queue->queued_bytes >= avail);
SDL_memcpy(ptr, packet->data + packet->startpos, cpy);
ptr += cpy;
len -= cpy;
}
return (size_t) (ptr - buf);
}
size_t
SDL_ReadFromDataQueue(SDL_DataQueue *queue, void *_buf, const size_t _len)
{
size_t len = _len;
Uint8 *buf = (Uint8 *) _buf;
Uint8 *ptr = buf;
SDL_DataQueuePacket *packet;
if (!queue) {
return 0;
}
while ((len > 0) && ((packet = queue->head) != NULL)) {
const size_t avail = packet->datalen - packet->startpos;
const size_t cpy = SDL_min(len, avail);
SDL_assert(queue->queued_bytes >= avail);
SDL_memcpy(ptr, packet->data + packet->startpos, cpy);
packet->startpos += cpy;
ptr += cpy;
queue->queued_bytes -= cpy;
len -= cpy;
if (packet->startpos == packet->datalen) { /* packet is done, put it in the pool. */
queue->head = packet->next;
SDL_assert((packet->next != NULL) || (packet == queue->tail));
packet->next = queue->pool;
queue->pool = packet;
}
}
SDL_assert((queue->head != NULL) == (queue->queued_bytes != 0));
if (queue->head == NULL) {
queue->tail = NULL; /* in case we drained the queue entirely. */
}
return (size_t) (ptr - buf);
}
size_t
SDL_CountDataQueue(SDL_DataQueue *queue)
{
return queue ? queue->queued_bytes : 0;
}
void *
SDL_ReserveSpaceInDataQueue(SDL_DataQueue *queue, const size_t len)
{
SDL_DataQueuePacket *packet;
if (!queue) {
SDL_InvalidParamError("queue");
return NULL;
} else if (len == 0) {
SDL_InvalidParamError("len");
return NULL;
} else if (len > queue->packet_size) {
SDL_SetError("len is larger than packet size");
return NULL;
}
packet = queue->head;
if (packet) {
const size_t avail = queue->packet_size - packet->datalen;
if (len <= avail) { /* we can use the space at end of this packet. */
void *retval = packet->data + packet->datalen;
packet->datalen += len;
queue->queued_bytes += len;
return retval;
}
}
/* Need a fresh packet. */
packet = AllocateDataQueuePacket(queue);
if (!packet) {
SDL_OutOfMemory();
return NULL;
}
packet->datalen = len;
queue->queued_bytes += len;
return packet->data;
}
/* vi: set ts=4 sw=4 expandtab: */
SDL_DataQueue
Definition: SDL_dataqueue.c:35
SDL_DataQueue::head
SDL_DataQueuePacket * head
Definition: SDL_dataqueue.c:37
SDL_min
#define SDL_min(x, y)
Definition: SDL_stdinc.h:406
SDL_WriteToDataQueue
int SDL_WriteToDataQueue(SDL_DataQueue *queue, const void *_data, const size_t _len)
Definition: SDL_dataqueue.c:175
SDL_internal.h
SDL_DataQueue::queued_bytes
size_t queued_bytes
Definition: SDL_dataqueue.c:41
SDL_DataQueue::pool
SDL_DataQueuePacket * pool
Definition: SDL_dataqueue.c:39
SDL_NewDataQueue
SDL_DataQueue * SDL_NewDataQueue(const size_t _packetlen, const size_t initialslack)
Definition: SDL_dataqueue.c:58
data
GLint GLenum GLsizei GLsizei GLsizei GLint GLsizei const GLvoid * data
Definition: SDL_opengl.h:1974
SDL_FreeDataQueueList
static void SDL_FreeDataQueueList(SDL_DataQueuePacket *packet)
Definition: SDL_dataqueue.c:45
SDL_InvalidParamError
#define SDL_InvalidParamError(param)
Definition: SDL_error.h:54
SDL_DataQueuePacket::data
Uint8 data[SDL_VARIABLE_LENGTH_ARRAY]
Definition: SDL_dataqueue.c:32
SDL_zerop
#define SDL_zerop(x)
Definition: SDL_stdinc.h:417
len
GLenum GLsizei len
Definition: SDL_opengl_glext.h:2926
SDL_DataQueuePacket::startpos
size_t startpos
Definition: SDL_dataqueue.c:30
retval
SDL_bool retval
Definition: testgamecontroller.c:65
SDL_DataQueuePacket::next
struct SDL_DataQueuePacket * next
Definition: SDL_dataqueue.c:31
SDL_memcpy
#define SDL_memcpy
Definition: SDL_dynapi_overrides.h:387
SDL_DataQueuePacket
Definition: SDL_dataqueue.c:27
SDL_dataqueue.h
Uint8
uint8_t Uint8
Definition: SDL_stdinc.h:157
SDL_free
#define SDL_free
Definition: SDL_dynapi_overrides.h:377
SDL_PeekIntoDataQueue
size_t SDL_PeekIntoDataQueue(SDL_DataQueue *queue, void *_buf, const size_t _len)
Definition: SDL_dataqueue.c:229
SDL_DataQueuePacket::datalen
size_t datalen
Definition: SDL_dataqueue.c:29
SDL_ReserveSpaceInDataQueue
void * SDL_ReserveSpaceInDataQueue(SDL_DataQueue *queue, const size_t len)
Definition: SDL_dataqueue.c:300
SDL_DataQueue::tail
SDL_DataQueuePacket * tail
Definition: SDL_dataqueue.c:38
SDL_ReadFromDataQueue
size_t SDL_ReadFromDataQueue(SDL_DataQueue *queue, void *_buf, const size_t _len)
Definition: SDL_dataqueue.c:254
AllocateDataQueuePacket
static SDL_DataQueuePacket * AllocateDataQueuePacket(SDL_DataQueue *queue)
Definition: SDL_dataqueue.c:141
buf
GLenum GLuint GLenum GLsizei const GLchar * buf
Definition: SDL_opengl_glext.h:2480
SDL_VARIABLE_LENGTH_ARRAY
#define SDL_VARIABLE_LENGTH_ARRAY
Definition: SDL_internal.h:35
i
return Display return Display Bool Bool int int int return Display XEvent Bool(*) XPointer return Display return Display Drawable _Xconst char unsigned int unsigned int return Display Pixmap Pixmap XColor XColor unsigned int unsigned int return Display _Xconst char char int char return Display Visual unsigned int int int char unsigned int unsigned int in i)
Definition: SDL_x11sym.h:50
SDL_assert
#define SDL_assert(condition)
Definition: SDL_assert.h:169
NULL
#define NULL
Definition: begin_code.h:164
SDL_OutOfMemory
#define SDL_OutOfMemory()
Definition: SDL_error.h:52
SDL_SetError
#define SDL_SetError
Definition: SDL_dynapi_overrides.h:30
SDL_ClearDataQueue
void SDL_ClearDataQueue(SDL_DataQueue *queue, const size_t slack)
Definition: SDL_dataqueue.c:98
SDL_CountDataQueue
size_t SDL_CountDataQueue(SDL_DataQueue *queue)
Definition: SDL_dataqueue.c:294
SDL_malloc
#define SDL_malloc
Definition: SDL_dynapi_overrides.h:374
SDL_FreeDataQueue
void SDL_FreeDataQueue(SDL_DataQueue *queue)
Definition: SDL_dataqueue.c:88
SDL.h
SDL_DataQueue::packet_size
size_t packet_size
Definition: SDL_dataqueue.c:40
SDL_assert.h