SDL_cpuinfo.h File Reference

#include "SDL_stdinc.h"
#include <immintrin.h>
#include "begin_code.h"
#include "close_code.h"

Include dependency graph for SDL_cpuinfo.h:

This graph shows which files directly or indirectly include this file:

Go to the source code of this file.

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.

Definition at line 133 of file SDL_dynapi_procs.h.

References cpuid, d, SDL_CACHELINE_SIZE, SDL_GetCPUType(), SDL_strcmp, and void.

SDL_GetCPUCount()

int SDL_GetCPUCount

(

void

)

This function returns the number of CPU cores available.

Definition at line 562 of file SDL_cpuinfo.c.

{
    if (!SDL_CPUCount) {
#ifndef SDL_CPUINFO_DISABLED
#if defined(HAVE_SYSCONF) && defined(_SC_NPROCESSORS_ONLN)
        if (SDL_CPUCount <= 0) {
            SDL_CPUCount = (int)sysconf(_SC_NPROCESSORS_ONLN);
        }
#endif
#ifdef HAVE_SYSCTLBYNAME
        if (SDL_CPUCount <= 0) {
            size_t size = sizeof(SDL_CPUCount);
            sysctlbyname("hw.ncpu", &SDL_CPUCount, &size, NULL, 0);
        }
#endif
#ifdef __WIN32__
        if (SDL_CPUCount <= 0) {
            SYSTEM_INFO info;
            GetSystemInfo(&info);
            SDL_CPUCount = info.dwNumberOfProcessors;
        }
#endif
#ifdef __OS2__
        if (SDL_CPUCount <= 0) {
            DosQuerySysInfo(QSV_NUMPROCESSORS, QSV_NUMPROCESSORS,
                            &SDL_CPUCount, sizeof(SDL_CPUCount) );
        }
#endif
#endif
        /* There has to be at least 1, right? :) */
        if (SDL_CPUCount <= 0) {
            SDL_CPUCount = 1;
        }
    }
    return SDL_CPUCount;
}

References int(), NULL, and SDL_CPUCount.

SDL_GetSystemRAM()

int SDL_GetSystemRAM

(

void

)

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

Definition at line 143 of file SDL_dynapi_procs.h.

References int(), NULL, and SDL_SystemRAM.

SDL_Has3DNow()

SDL_bool SDL_Has3DNow

(

void

)

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

Definition at line 137 of file SDL_dynapi_procs.h.

References CPU_FEATURE_AVAILABLE, and CPU_HAS_3DNOW.

SDL_HasAltiVec()

SDL_bool SDL_HasAltiVec

(

void

)

This function returns true if the CPU has AltiVec features.

Definition at line 135 of file SDL_dynapi_procs.h.

References CPU_FEATURE_AVAILABLE, and CPU_HAS_ALTIVEC.

SDL_HasARMSIMD()

SDL_bool SDL_HasARMSIMD

(

void

)

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

Definition at line 872 of file SDL_cpuinfo.c.

{
    return CPU_FEATURE_AVAILABLE(CPU_HAS_ARM_SIMD);
}

References CPU_FEATURE_AVAILABLE, and CPU_HAS_ARM_SIMD.

SDL_HasAVX()

SDL_bool SDL_HasAVX

(

void

)

This function returns true if the CPU has AVX features.

Definition at line 599 of file SDL_dynapi_procs.h.

References CPU_FEATURE_AVAILABLE, and CPU_HAS_AVX.

SDL_HasAVX2()

SDL_bool SDL_HasAVX2

(

void

)

This function returns true if the CPU has AVX2 features.

Definition at line 860 of file SDL_cpuinfo.c.

{
    return CPU_FEATURE_AVAILABLE(CPU_HAS_AVX2);
}

References CPU_FEATURE_AVAILABLE, and CPU_HAS_AVX2.

SDL_HasAVX512F()

SDL_bool SDL_HasAVX512F

(

void

)

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

Definition at line 866 of file SDL_cpuinfo.c.

{
    return CPU_FEATURE_AVAILABLE(CPU_HAS_AVX512F);
}

References CPU_FEATURE_AVAILABLE, and CPU_HAS_AVX512F.

SDL_HasMMX()

SDL_bool SDL_HasMMX

(

void

)

This function returns true if the CPU has MMX features.

Definition at line 812 of file SDL_cpuinfo.c.

{
    return CPU_FEATURE_AVAILABLE(CPU_HAS_MMX);
}

References CPU_FEATURE_AVAILABLE, and CPU_HAS_MMX.

SDL_HasNEON()

SDL_bool SDL_HasNEON

(

void

)

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

Definition at line 652 of file SDL_dynapi_procs.h.

References CPU_FEATURE_AVAILABLE, and CPU_HAS_NEON.

SDL_HasRDTSC()

SDL_bool SDL_HasRDTSC

(

void

)

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

Definition at line 800 of file SDL_cpuinfo.c.

{
    return CPU_FEATURE_AVAILABLE(CPU_HAS_RDTSC);
}

References CPU_FEATURE_AVAILABLE, and CPU_HAS_RDTSC.

SDL_HasSSE()

SDL_bool SDL_HasSSE

(

void

)

This function returns true if the CPU has SSE features.

Definition at line 824 of file SDL_cpuinfo.c.

{
    return CPU_FEATURE_AVAILABLE(CPU_HAS_SSE);
}

References CPU_FEATURE_AVAILABLE, and CPU_HAS_SSE.

SDL_HasSSE2()

SDL_bool SDL_HasSSE2

(

void

)

This function returns true if the CPU has SSE2 features.

Definition at line 139 of file SDL_dynapi_procs.h.

References CPU_FEATURE_AVAILABLE, and CPU_HAS_SSE2.

SDL_HasSSE3()

SDL_bool SDL_HasSSE3

(

void

)

This function returns true if the CPU has SSE3 features.

Definition at line 836 of file SDL_cpuinfo.c.

{
    return CPU_FEATURE_AVAILABLE(CPU_HAS_SSE3);
}

References CPU_FEATURE_AVAILABLE, and CPU_HAS_SSE3.

SDL_HasSSE41()

SDL_bool SDL_HasSSE41

(

void

)

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

Definition at line 141 of file SDL_dynapi_procs.h.

References CPU_FEATURE_AVAILABLE, and CPU_HAS_SSE41.

SDL_HasSSE42()

SDL_bool SDL_HasSSE42

(

void

)

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

Definition at line 848 of file SDL_cpuinfo.c.

{
    return CPU_FEATURE_AVAILABLE(CPU_HAS_SSE42);
}

References CPU_FEATURE_AVAILABLE, and CPU_HAS_SSE42.

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

len	The 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

Definition at line 957 of file SDL_cpuinfo.c.

{
    const size_t alignment = SDL_SIMDGetAlignment();
    const size_t padding = alignment - (len % alignment);
    const size_t padded = (padding != alignment) ? (len + padding) : len;
    Uint8 *retval = NULL;
    Uint8 *ptr = (Uint8 *) SDL_malloc(padded + alignment + sizeof (void *));
    if (ptr) {
        /* store the actual malloc pointer right before our aligned pointer. */
        retval = ptr + sizeof (void *);
        retval += alignment - (((size_t) retval) % alignment);
        *(((void **) retval) - 1) = ptr;
    }
    return retval;
}

References NULL, ptr, retval, SDL_malloc, and SDL_SIMDGetAlignment().

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

Definition at line 1026 of file SDL_cpuinfo.c.

{
    if (ptr) {
        void **realptr = (void **) ptr;
        realptr--;
        SDL_free(*(((void **) ptr) - 1));
    }
}

References ptr, and SDL_free.

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.

Definition at line 773 of file SDL_dynapi_procs.h.

References SDL_assert, SDL_GetCPUFeatures(), and SDL_SIMDAlignment.

Referenced by SDL_SIMDAlloc(), and SDL_SIMDRealloc().

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

mem	The 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.
len	The 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

Definition at line 974 of file SDL_cpuinfo.c.

{
    const size_t alignment = SDL_SIMDGetAlignment();
    const size_t padding = alignment - (len % alignment);
    const size_t padded = (padding != alignment) ? (len + padding) : len;
    Uint8 *retval = (Uint8*) mem;
    void *oldmem = mem;
    size_t memdiff = 0, ptrdiff;
    Uint8 *ptr;
 
    if (mem) {
        void **realptr = (void **) mem;
        realptr--;
        mem = *(((void **) mem) - 1);
 
        /* Check the delta between the real pointer and user pointer */
        memdiff = ((size_t) oldmem) - ((size_t) mem);
    }
 
    ptr = (Uint8 *) SDL_realloc(mem, padded + alignment + sizeof (void *));
 
    if (ptr == mem) {
        return retval; /* Pointer didn't change, nothing to do */
    }
    if (ptr == NULL) {
        return NULL; /* Out of memory, bail! */
    }
 
    /* Store the actual malloc pointer right before our aligned pointer. */
    retval = ptr + sizeof (void *);
    retval += alignment - (((size_t) retval) % alignment);
 
    /* Make sure the delta is the same! */
    if (mem) {
        ptrdiff = ((size_t) retval) - ((size_t) ptr);
        if (memdiff != ptrdiff) { /* Delta has changed, copy to new offset! */
            oldmem = (void*) (((size_t) ptr) + memdiff);
 
            /* Even though the data past the old `len` is undefined, this is the
             * only length value we have, and it guarantees that we copy all the
             * previous memory anyhow.
             */
            SDL_memmove(retval, oldmem, len);
        }
    }
 
    /* Actually store the malloc pointer, finally. */
    *(((void **) retval) - 1) = ptr;
    return retval;
}

References NULL, ptr, retval, SDL_memmove, SDL_realloc, and SDL_SIMDGetAlignment().