cpuinfo.nim

CPU feature detection for SDL.

Consts

CACHELINE_SIZE* = 128: This is a guess for the cacheline size used for padding. Most x86 processors have a 64 byte cache line. The 64-bit PowerPC processors have a 128 byte cache line. We'll use the larger value to be generally safe.

Procs

proc getCPUCount*(): cint {...}{.cdecl, importc: "SDL_GetCPUCount", dynlib: SDL2_LIB.}

This procedure returns the number of CPU cores available.

proc getCPUCacheLineSize*(): cint {...}{.cdecl, importc: "SDL_GetCPUCacheLineSize", dynlib: SDL2_LIB.}

This procedure returns the L1 cache line size of the CPU

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

proc hasRDTSC*(): bool {...}{.cdecl, importc: "SDL_HasRDTSC", dynlib: SDL2_LIB.}

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

proc hasAltiVec*(): bool {...}{.cdecl, importc: "SDL_HasAltiVec", dynlib: SDL2_LIB.}

This procedure returns true if the CPU has AltiVec features.

proc hasMMX*(): bool {...}{.cdecl, importc: "SDL_HasMMX", dynlib: SDL2_LIB.}

This procedure returns true if the CPU has MMX features.

proc has3DNow*(): bool {...}{.cdecl, importc: "SDL_Has3DNow", dynlib: SDL2_LIB.}

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

proc hasSSE*(): bool {...}{.cdecl, importc: "SDL_HasSSE", dynlib: SDL2_LIB.}

This procedure returns true if the CPU has SSE features.

proc hasSSE2*(): bool {...}{.cdecl, importc: "SDL_HasSSE2", dynlib: SDL2_LIB.}

This procedure returns true if the CPU has SSE2 features.

proc hasSSE3*(): bool {...}{.cdecl, importc: "SDL_HasSSE3", dynlib: SDL2_LIB.}

This procedure returns true if the CPU has SSE3 features.

proc hasSSE41*(): bool {...}{.cdecl, importc: "SDL_HasSSE41", dynlib: SDL2_LIB.}

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

proc hasSSE42*(): bool {...}{.cdecl, importc: "SDL_HasSSE42", dynlib: SDL2_LIB.}

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

proc hasAVX*(): bool {...}{.cdecl, importc: "SDL_HasAVX", dynlib: SDL2_LIB.}

This procedure returns true if the CPU has AVX features.

proc hasAVX2*(): bool {...}{.cdecl, importc: "SDL_HasAVX2", dynlib: SDL2_LIB.}

This procedure returns true if the CPU has AVX2 features.

proc hasAVX512F*(): bool {...}{.cdecl, importc: "SDL_HasAVX512F", dynlib: SDL2_LIB.}

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

proc hasARMSIMD*(): bool {...}{.cdecl, importc: "SDL_HasARMSIMD", dynlib: SDL2_LIB.}

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

proc hasNEON*(): bool {...}{.cdecl, importc: "SDL_HasNEON", dynlib: SDL2_LIB.}

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

proc getSystemRAM*(): cint {...}{.cdecl, importc: "SDL_GetSystemRAM", dynlib: SDL2_LIB.}

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

proc simdGetAlignment*(): csize_t {...}{.cdecl, importc: "SDL_SIMDGetAlignment", dynlib: SDL2_LIB.}

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.

proc simdAlloc*(len: csize_t): pointer {...}{.cdecl, importc: "SDL_SIMDAlloc", dynlib: SDL2_LIB.}

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() 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...() procedure, don't use that instruction set with memory allocated through here.

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

len The length, in bytes, of the block to allocated. The actual allocated block might be larger due to padding, etc.

Return pointer to newly-allocated block, nil if out of memory.