SDL 3.0
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#include <SDL3/SDL_stdinc.h>
#include <SDL3/SDL_error.h>
#include <SDL3/SDL_properties.h>
#include <SDL3/SDL_begin_code.h>
#include <SDL3/SDL_close_code.h>
Go to the source code of this file.
Data Structures | |
struct | SDL_IOStreamInterface |
Typedefs | |
typedef struct SDL_IOStream | SDL_IOStream |
Enumerations | |
enum | SDL_IOStatus { SDL_IO_STATUS_READY , SDL_IO_STATUS_ERROR , SDL_IO_STATUS_EOF , SDL_IO_STATUS_NOT_READY , SDL_IO_STATUS_READONLY , SDL_IO_STATUS_WRITEONLY } |
This file provides a general interface for SDL to read and write data streams. It can easily be extended to files, memory, etc.
SDL_IOStream is not related to the standard C++ iostream class, other than both are abstract interfaces to read/write data.
Definition in file SDL_iostream.h.
#define SDL_IO_SEEK_CUR 1 |
Seek relative to current read point
Definition at line 379 of file SDL_iostream.h.
#define SDL_IO_SEEK_END 2 |
Seek relative to the end of data
Definition at line 380 of file SDL_iostream.h.
#define SDL_IO_SEEK_SET 0 |
Seek from the beginning of data
Definition at line 378 of file SDL_iostream.h.
#define SDL_PROP_IOSTREAM_ANDROID_AASSET_POINTER "SDL.iostream.android.aasset" |
Definition at line 219 of file SDL_iostream.h.
#define SDL_PROP_IOSTREAM_DYNAMIC_CHUNKSIZE_NUMBER "SDL.iostream.dynamic.chunksize" |
Definition at line 310 of file SDL_iostream.h.
#define SDL_PROP_IOSTREAM_DYNAMIC_MEMORY_POINTER "SDL.iostream.dynamic.memory" |
Definition at line 309 of file SDL_iostream.h.
#define SDL_PROP_IOSTREAM_STDIO_FILE_POINTER "SDL.iostream.stdio.file" |
Definition at line 218 of file SDL_iostream.h.
#define SDL_PROP_IOSTREAM_WINDOWS_HANDLE_POINTER "SDL.iostream.windows.handle" |
Definition at line 217 of file SDL_iostream.h.
typedef struct SDL_IOStream SDL_IOStream |
The read/write operation structure.
This operates as an opaque handle. There are several APIs to create various types of I/O streams, or an app can supply an SDL_IOStreamInterface to SDL_OpenIO() to provide their own stream implementation behind this struct's abstract interface.
Definition at line 129 of file SDL_iostream.h.
enum SDL_IOStatus |
Definition at line 46 of file SDL_iostream.h.
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Close and free an allocated SDL_IOStream structure.
SDL_CloseIO() closes and cleans up the SDL_IOStream stream. It releases any resources used by the stream and frees the SDL_IOStream itself. This returns 0 on success, or -1 if the stream failed to flush to its output (e.g. to disk).
Note that if this fails to flush the stream to disk, this function reports an error, but the SDL_IOStream is still invalid once this function returns.
context | SDL_IOStream structure to close |
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Get the properties associated with an SDL_IOStream.
context | a pointer to an SDL_IOStream structure |
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Use this function to get the size of the data stream in an SDL_IOStream.
context | the SDL_IOStream to get the size of the data stream from |
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Query the stream status of an SDL_IOStream.
This information can be useful to decide if a short read or write was due to an error, an EOF, or a non-blocking operation that isn't yet ready to complete.
An SDL_IOStream's status is only expected to change after a SDL_ReadIO or SDL_WriteIO call; don't expect it to change if you just call this query function in a tight loop.
context | the SDL_IOStream to query. |
\threadsafety This function should not be called at the same time that another thread is operating on the same SDL_IOStream.
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Use this function to prepare a read-only memory buffer for use with SDL_IOStream.
This function sets up an SDL_IOStream struct based on a memory area of a certain size. It assumes the memory area is not writable.
Attempting to write to this SDL_IOStream stream will report an error without writing to the memory buffer.
This memory buffer is not copied by the SDL_IOStream; the pointer you provide must remain valid until you close the stream. Closing the stream will not free the original buffer.
If you need to write to a memory buffer, you should use SDL_IOFromMem() with a writable buffer of memory instead.
mem | a pointer to a read-only buffer to feed an SDL_IOStream stream |
size | the buffer size, in bytes |
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Use this function to create an SDL_IOStream that is backed by dynamically allocated memory.
This supports the following properties to provide access to the memory and control over allocations: - SDL_PROP_IOSTREAM_DYNAMIC_MEMORY_POINTER
: a pointer to the internal memory of the stream. This can be set to NULL to transfer ownership of the memory to the application, which should free the memory with SDL_free(). If this is done, the next operation on the stream must be SDL_CloseIO(). - SDL_PROP_IOSTREAM_DYNAMIC_CHUNKSIZE_NUMBER
: memory will be allocated in multiples of this size, defaulting to 1024.
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Use this function to create a new SDL_IOStream structure for reading from and/or writing to a named file.
The mode
string is treated roughly the same as in a call to the C library's fopen(), even if SDL doesn't happen to use fopen() behind the scenes.
Available mode
strings:
NOTE: In order to open a file as a binary file, a "b" character has to be included in the mode
string. This additional "b" character can either be appended at the end of the string (thus making the following compound modes: "rb", "wb", "ab", "r+b", "w+b", "a+b") or be inserted between the letter and the "+" sign for the mixed modes ("rb+", "wb+", "ab+"). Additional characters may follow the sequence, although they should have no effect. For example, "t" is sometimes appended to make explicit the file is a text file.
This function supports Unicode filenames, but they must be encoded in UTF-8 format, regardless of the underlying operating system.
As a fallback, SDL_IOFromFile() will transparently open a matching filename in an Android app's assets
.
Closing the SDL_IOStream will close SDL's internal file handle.
The following properties may be set at creation time by SDL:
SDL_PROP_IOSTREAM_WINDOWS_HANDLE_POINTER
: a pointer, that can be cast to a win32 HANDLE
, that this SDL_IOStream is using to access the filesystem. If the program isn't running on Windows, or SDL used some other method to access the filesystem, this property will not be set.SDL_PROP_IOSTREAM_STDIO_FILE_POINTER
: a pointer, that can be cast to a stdio FILE *
, that this SDL_IOStream is using to access the filesystem. If SDL used some other method to access the filesystem, this property will not be set. PLEASE NOTE that if SDL is using a different C runtime than your app, trying to use this pointer will almost certainly result in a crash! This is mostly a problem on Windows; make sure you build SDL and your app with the same compiler and settings to avoid it.SDL_PROP_IOSTREAM_ANDROID_AASSET_POINTER
: a pointer, that can be cast to an Android NDK AAsset *
, that this SDL_IOStream is using to access the filesystem. If SDL used some other method to access the filesystem, this property will not be set.file | a UTF-8 string representing the filename to open |
mode | an ASCII string representing the mode to be used for opening the file. |
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Use this function to prepare a read-write memory buffer for use with SDL_IOStream.
This function sets up an SDL_IOStream struct based on a memory area of a certain size, for both read and write access.
This memory buffer is not copied by the SDL_IOStream; the pointer you provide must remain valid until you close the stream. Closing the stream will not free the original buffer.
If you need to make sure the SDL_IOStream never writes to the memory buffer, you should use SDL_IOFromConstMem() with a read-only buffer of memory instead.
mem | a pointer to a buffer to feed an SDL_IOStream stream |
size | the buffer size, in bytes |
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Print to an SDL_IOStream data stream.
This function does formatted printing to the stream.
context | a pointer to an SDL_IOStream structure |
fmt | a printf() style format string |
... | additional parameters matching % tokens in the fmt string, if any |
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Print to an SDL_IOStream data stream.
This function does formatted printing to the stream.
context | a pointer to an SDL_IOStream structure |
fmt | a printf() style format string |
ap | a variable argument list |
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Load all the data from a file path.
The data is allocated with a zero byte at the end (null terminated) for convenience. This extra byte is not included in the value reported via datasize
.
The data should be freed with SDL_free().
file | the path to read all available data from |
datasize | if not NULL, will store the number of bytes read |
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Load all the data from an SDL data stream.
The data is allocated with a zero byte at the end (null terminated) for convenience. This extra byte is not included in the value reported via datasize
.
The data should be freed with SDL_free().
src | the SDL_IOStream to read all available data from |
datasize | if not NULL, will store the number of bytes read |
closeio | if SDL_TRUE, calls SDL_CloseIO() on src before returning, even in the case of an error |
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Create a custom SDL_IOStream.
Applications do not need to use this function unless they are providing their own SDL_IOStream implementation. If you just need an SDL_IOStream to read/write a common data source, you should use the built-in implementations in SDL, like SDL_IOFromFile() or SDL_IOFromMem(), etc.
You must free the returned pointer with SDL_CloseIO().
This function makes a copy of iface
and the caller does not need to keep this data around after this call.
iface | The function pointers that implement this SDL_IOStream. |
userdata | The app-controlled pointer that is passed to iface's functions when called. |
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Read from a data source.
This function reads up size
bytes from the data source to the area pointed at by ptr
. This function may read less bytes than requested. It will return zero when the data stream is completely read, or on error. To determine if there was an error or all data was read, call SDL_GetIOStatus().
context | a pointer to an SDL_IOStream structure |
ptr | a pointer to a buffer to read data into |
size | the number of bytes to read from the data source. |
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Use this function to read 16 bits of big-endian data from an SDL_IOStream and return in native format.
SDL byteswaps the data only if necessary, so the data returned will be in the native byte order.
src | the stream from which to read data |
value | a pointer filled in with the data read |
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Use this function to read 16 bits of little-endian data from an SDL_IOStream and return in native format.
SDL byteswaps the data only if necessary, so the data returned will be in the native byte order.
src | the stream from which to read data |
value | a pointer filled in with the data read |
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Use this function to read 32 bits of big-endian data from an SDL_IOStream and return in native format.
SDL byteswaps the data only if necessary, so the data returned will be in the native byte order.
src | the stream from which to read data |
value | a pointer filled in with the data read |
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Use this function to read 32 bits of little-endian data from an SDL_IOStream and return in native format.
SDL byteswaps the data only if necessary, so the data returned will be in the native byte order.
src | the stream from which to read data |
value | a pointer filled in with the data read |
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Use this function to read 64 bits of big-endian data from an SDL_IOStream and return in native format.
SDL byteswaps the data only if necessary, so the data returned will be in the native byte order.
src | the stream from which to read data |
value | a pointer filled in with the data read |
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Use this function to read 64 bits of little-endian data from an SDL_IOStream and return in native format.
SDL byteswaps the data only if necessary, so the data returned will be in the native byte order.
src | the stream from which to read data |
value | a pointer filled in with the data read |
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Use this function to read 16 bits of big-endian data from an SDL_IOStream and return in native format.
SDL byteswaps the data only if necessary, so the data returned will be in the native byte order.
src | the stream from which to read data |
value | a pointer filled in with the data read |
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Use this function to read 16 bits of little-endian data from an SDL_IOStream and return in native format.
SDL byteswaps the data only if necessary, so the data returned will be in the native byte order.
src | the stream from which to read data |
value | a pointer filled in with the data read |
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Use this function to read 32 bits of big-endian data from an SDL_IOStream and return in native format.
SDL byteswaps the data only if necessary, so the data returned will be in the native byte order.
src | the stream from which to read data |
value | a pointer filled in with the data read |
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Use this function to read 32 bits of little-endian data from an SDL_IOStream and return in native format.
SDL byteswaps the data only if necessary, so the data returned will be in the native byte order.
src | the stream from which to read data |
value | a pointer filled in with the data read |
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Use this function to read 64 bits of big-endian data from an SDL_IOStream and return in native format.
SDL byteswaps the data only if necessary, so the data returned will be in the native byte order.
src | the stream from which to read data |
value | a pointer filled in with the data read |
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Use this function to read 64 bits of little-endian data from an SDL_IOStream and return in native format.
SDL byteswaps the data only if necessary, so the data returned will be in the native byte order.
src | the stream from which to read data |
value | a pointer filled in with the data read |
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Use this function to read a byte from an SDL_IOStream.
src | the SDL_IOStream to read from |
value | a pointer filled in with the data read |
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Seek within an SDL_IOStream data stream.
This function seeks to byte offset
, relative to whence
.
whence
may be any of the following values:
SDL_IO_SEEK_SET
: seek from the beginning of dataSDL_IO_SEEK_CUR
: seek relative to current read pointSDL_IO_SEEK_END
: seek relative to the end of dataIf this stream can not seek, it will return -1.
context | a pointer to an SDL_IOStream structure |
offset | an offset in bytes, relative to whence location; can be negative |
whence | any of SDL_IO_SEEK_SET , SDL_IO_SEEK_CUR , SDL_IO_SEEK_END |
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Determine the current read/write offset in an SDL_IOStream data stream.
SDL_TellIO is actually a wrapper function that calls the SDL_IOStream's seek
method, with an offset of 0 bytes from SDL_IO_SEEK_CUR
, to simplify application development.
context | an SDL_IOStream data stream object from which to get the current offset |
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Write to an SDL_IOStream data stream.
This function writes exactly size
bytes from the area pointed at by ptr
to the stream. If this fails for any reason, it'll return less than size
to demonstrate how far the write progressed. On success, it returns size
.
On error, this function still attempts to write as much as possible, so it might return a positive value less than the requested write size.
The caller can use SDL_GetIOStatus() to determine if the problem is recoverable, such as a non-blocking write that can simply be retried later, or a fatal error.
context | a pointer to an SDL_IOStream structure |
ptr | a pointer to a buffer containing data to write |
size | the number of bytes to write |
size
on error; call SDL_GetError() for more information.
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Use this function to write 16 bits in native format to an SDL_IOStream as big-endian data.
SDL byteswaps the data only if necessary, so the application always specifies native format, and the data written will be in big-endian format.
dst | the stream to which data will be written |
value | the data to be written, in native format |
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Use this function to write 16 bits in native format to an SDL_IOStream as little-endian data.
SDL byteswaps the data only if necessary, so the application always specifies native format, and the data written will be in little-endian format.
dst | the stream to which data will be written |
value | the data to be written, in native format |
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Use this function to write 32 bits in native format to an SDL_IOStream as big-endian data.
SDL byteswaps the data only if necessary, so the application always specifies native format, and the data written will be in big-endian format.
dst | the stream to which data will be written |
value | the data to be written, in native format |
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Use this function to write 32 bits in native format to an SDL_IOStream as little-endian data.
SDL byteswaps the data only if necessary, so the application always specifies native format, and the data written will be in little-endian format.
dst | the stream to which data will be written |
value | the data to be written, in native format |
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Use this function to write 64 bits in native format to an SDL_IOStream as big-endian data.
SDL byteswaps the data only if necessary, so the application always specifies native format, and the data written will be in big-endian format.
dst | the stream to which data will be written |
value | the data to be written, in native format |
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Use this function to write 64 bits in native format to an SDL_IOStream as little-endian data.
SDL byteswaps the data only if necessary, so the application always specifies native format, and the data written will be in little-endian format.
dst | the stream to which data will be written |
value | the data to be written, in native format |
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Use this function to write 16 bits in native format to an SDL_IOStream as big-endian data.
SDL byteswaps the data only if necessary, so the application always specifies native format, and the data written will be in big-endian format.
dst | the stream to which data will be written |
value | the data to be written, in native format |
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Use this function to write 16 bits in native format to an SDL_IOStream as little-endian data.
SDL byteswaps the data only if necessary, so the application always specifies native format, and the data written will be in little-endian format.
dst | the stream to which data will be written |
value | the data to be written, in native format |
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Use this function to write 32 bits in native format to an SDL_IOStream as big-endian data.
SDL byteswaps the data only if necessary, so the application always specifies native format, and the data written will be in big-endian format.
dst | the stream to which data will be written |
value | the data to be written, in native format |
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Use this function to write 32 bits in native format to an SDL_IOStream as little-endian data.
SDL byteswaps the data only if necessary, so the application always specifies native format, and the data written will be in little-endian format.
dst | the stream to which data will be written |
value | the data to be written, in native format |
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Use this function to write 64 bits in native format to an SDL_IOStream as big-endian data.
SDL byteswaps the data only if necessary, so the application always specifies native format, and the data written will be in big-endian format.
dst | the stream to which data will be written |
value | the data to be written, in native format |
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Use this function to write 64 bits in native format to an SDL_IOStream as little-endian data.
SDL byteswaps the data only if necessary, so the application always specifies native format, and the data written will be in little-endian format.
dst | the stream to which data will be written |
value | the data to be written, in native format |
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Use this function to write a byte to an SDL_IOStream.
dst | the SDL_IOStream to write to |
value | the byte value to write |