SDL  2.0
SDL_cpuinfo.h File Reference
#include "SDL_stdinc.h"
#include <immintrin.h>
#include "begin_code.h"
#include "close_code.h"
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Macros

#define SDL_CACHELINE_SIZE   128
 

Functions

int SDL_GetCPUCount (void)
 
int SDL_GetCPUCacheLineSize (void)
 
SDL_bool SDL_HasRDTSC (void)
 
SDL_bool SDL_HasAltiVec (void)
 
SDL_bool SDL_HasMMX (void)
 
SDL_bool SDL_Has3DNow (void)
 
SDL_bool SDL_HasSSE (void)
 
SDL_bool SDL_HasSSE2 (void)
 
SDL_bool SDL_HasSSE3 (void)
 
SDL_bool SDL_HasSSE41 (void)
 
SDL_bool SDL_HasSSE42 (void)
 
SDL_bool SDL_HasAVX (void)
 
SDL_bool SDL_HasAVX2 (void)
 
SDL_bool SDL_HasAVX512F (void)
 
SDL_bool SDL_HasARMSIMD (void)
 
SDL_bool SDL_HasNEON (void)
 
int SDL_GetSystemRAM (void)
 
size_t SDL_SIMDGetAlignment (void)
 Report the alignment this system needs for SIMD allocations. More...
 
void * SDL_SIMDAlloc (const size_t len)
 Allocate memory in a SIMD-friendly way. More...
 
void * SDL_SIMDRealloc (void *mem, const size_t len)
 Reallocate memory obtained from SDL_SIMDAlloc. More...
 
void SDL_SIMDFree (void *ptr)
 Deallocate memory obtained from SDL_SIMDAlloc. More...
 

Detailed Description

CPU feature detection for SDL.

Definition in file SDL_cpuinfo.h.

Macro Definition Documentation

◆ SDL_CACHELINE_SIZE

#define SDL_CACHELINE_SIZE   128

Definition at line 114 of file SDL_cpuinfo.h.

Function Documentation

◆ SDL_GetCPUCacheLineSize()

int SDL_GetCPUCacheLineSize ( void  )

This function returns the L1 cache line size of the CPU

This is useful for determining multi-threaded structure padding or SIMD prefetch sizes.

◆ SDL_GetCPUCount()

int SDL_GetCPUCount ( void  )

This function returns the number of CPU cores available.

◆ SDL_GetSystemRAM()

int SDL_GetSystemRAM ( void  )

This function returns the amount of RAM configured in the system, in MB.

◆ SDL_Has3DNow()

SDL_bool SDL_Has3DNow ( void  )

This function returns true if the CPU has 3DNow! features.

◆ SDL_HasAltiVec()

SDL_bool SDL_HasAltiVec ( void  )

This function returns true if the CPU has AltiVec features.

◆ SDL_HasARMSIMD()

SDL_bool SDL_HasARMSIMD ( void  )

This function returns true if the CPU has ARM SIMD (ARMv6) features.

◆ SDL_HasAVX()

SDL_bool SDL_HasAVX ( void  )

This function returns true if the CPU has AVX features.

◆ SDL_HasAVX2()

SDL_bool SDL_HasAVX2 ( void  )

This function returns true if the CPU has AVX2 features.

◆ SDL_HasAVX512F()

SDL_bool SDL_HasAVX512F ( void  )

This function returns true if the CPU has AVX-512F (foundation) features.

◆ SDL_HasMMX()

SDL_bool SDL_HasMMX ( void  )

This function returns true if the CPU has MMX features.

◆ SDL_HasNEON()

SDL_bool SDL_HasNEON ( void  )

This function returns true if the CPU has NEON (ARM SIMD) features.

◆ SDL_HasRDTSC()

SDL_bool SDL_HasRDTSC ( void  )

This function returns true if the CPU has the RDTSC instruction.

◆ SDL_HasSSE()

SDL_bool SDL_HasSSE ( void  )

This function returns true if the CPU has SSE features.

◆ SDL_HasSSE2()

SDL_bool SDL_HasSSE2 ( void  )

This function returns true if the CPU has SSE2 features.

◆ SDL_HasSSE3()

SDL_bool SDL_HasSSE3 ( void  )

This function returns true if the CPU has SSE3 features.

◆ SDL_HasSSE41()

SDL_bool SDL_HasSSE41 ( void  )

This function returns true if the CPU has SSE4.1 features.

◆ SDL_HasSSE42()

SDL_bool SDL_HasSSE42 ( void  )

This function returns true if the CPU has SSE4.2 features.

◆ SDL_SIMDAlloc()

void* SDL_SIMDAlloc ( const size_t  len)

Allocate memory in a SIMD-friendly way.

This will allocate a block of memory that is suitable for use with SIMD instructions. Specifically, it will be properly aligned and padded for the system's supported vector instructions.

The memory returned will be padded such that it is safe to read or write an incomplete vector at the end of the memory block. This can be useful so you don't have to drop back to a scalar fallback at the end of your SIMD processing loop to deal with the final elements without overflowing the allocated buffer.

You must free this memory with SDL_FreeSIMD(), not free() or SDL_free() or delete[], etc.

Note that SDL will only deal with SIMD instruction sets it is aware of; for example, SDL 2.0.8 knows that SSE wants 16-byte vectors (SDL_HasSSE()), and AVX2 wants 32 bytes (SDL_HasAVX2()), but doesn't know that AVX-512 wants 64. To be clear: if you can't decide to use an instruction set with an SDL_Has*() function, don't use that instruction set with memory allocated through here.

SDL_AllocSIMD(0) will return a non-NULL pointer, assuming the system isn't out of memory.

Parameters
lenThe length, in bytes, of the block to allocated. The actual allocated block might be larger due to padding, etc.
Returns
Pointer to newly-allocated block, NULL if out of memory.
See also
SDL_SIMDAlignment
SDL_SIMDRealloc
SDL_SIMDFree

◆ SDL_SIMDFree()

void SDL_SIMDFree ( void *  ptr)

Deallocate memory obtained from SDL_SIMDAlloc.

It is not valid to use this function on a pointer from anything but SDL_SIMDAlloc(). It can't be used on pointers from malloc, realloc, SDL_malloc, memalign, new[], etc.

However, SDL_SIMDFree(NULL) is a legal no-op.

See also
SDL_SIMDAlloc
SDL_SIMDRealloc

◆ SDL_SIMDGetAlignment()

size_t SDL_SIMDGetAlignment ( void  )

Report the alignment this system needs for SIMD allocations.

This will return the minimum number of bytes to which a pointer must be aligned to be compatible with SIMD instructions on the current machine. For example, if the machine supports SSE only, it will return 16, but if it supports AVX-512F, it'll return 64 (etc). This only reports values for instruction sets SDL knows about, so if your SDL build doesn't have SDL_HasAVX512F(), then it might return 16 for the SSE support it sees and not 64 for the AVX-512 instructions that exist but SDL doesn't know about. Plan accordingly.

◆ SDL_SIMDRealloc()

void* SDL_SIMDRealloc ( void *  mem,
const size_t  len 
)

Reallocate memory obtained from SDL_SIMDAlloc.

It is not valid to use this function on a pointer from anything but SDL_SIMDAlloc(). It can't be used on pointers from malloc, realloc, SDL_malloc, memalign, new[], etc.

Parameters
memThe pointer obtained from SDL_SIMDAlloc. This function also accepts NULL, at which point this function is the same as calling SDL_realloc with a NULL pointer.
lenThe length, in bytes, of the block to allocated. The actual allocated block might be larger due to padding, etc. Passing 0 will return a non-NULL pointer, assuming the system isn't out of memory.
Returns
Pointer to newly-reallocated block, NULL if out of memory.
See also
SDL_SIMDAlignment
SDL_SIMDAlloc
SDL_SIMDFree