codebox/base64/codec_choose.c

#include <stdbool.h>
#include <stdint.h>
#include <stddef.h>
#include <stdint.h>

#include "libbase64.h"
#include "codecs.h"

#if (__x86_64__ || __i386__ || _M_X86 || _M_X64)
  #define BASE64_X86
#endif

#ifdef BASE64_X86
#ifdef _MSC_VER
	#include <intrin.h>
	#define __cpuid_count(__level, __count, __eax, __ebx, __ecx, __edx) \
	{						\
		int info[4];				\
		__cpuidex(info, __level, __count);	\
		__eax = info[0];			\
		__ebx = info[1];			\
		__ecx = info[2];			\
		__edx = info[3];			\
	}
	#define __cpuid(__level, __eax, __ebx, __ecx, __edx) \
		__cpuid_count(__level, 0, __eax, __ebx, __ecx, __edx)
#else
	#include <cpuid.h>
#endif

#ifndef bit_AVX2
#define bit_AVX2 (1 << 5)
#endif
#ifndef bit_SSSE3
#define bit_SSSE3 (1 << 9)
#endif
#ifndef bit_SSE41
#define bit_SSE41 (1 << 19)
#endif
#ifndef bit_SSE42
#define bit_SSE42 (1 << 20)
#endif
#ifndef bit_AVX
#define bit_AVX (1 << 28)
#endif

#define bit_XSAVE_XRSTORE (1 << 27)

#ifndef _XCR_XFEATURE_ENABLED_MASK
#define _XCR_XFEATURE_ENABLED_MASK 0
#endif

#define _XCR_XMM_AND_YMM_STATE_ENABLED_BY_OS 0x6
#endif

// Function declarations:
#define BASE64_CODEC_FUNCS(arch)	\
	BASE64_ENC_FUNCTION(arch);	\
	BASE64_DEC_FUNCTION(arch);	\

BASE64_CODEC_FUNCS(plain)

static bool
codec_choose_forced (struct codec *codec, int flags)
{
	// If the user wants to use a certain codec,
	// always allow it, even if the codec is a no-op.
	// For testing purposes.

	if (!(flags & 0xFF)) {
		return false;
	}
	codec->enc = base64_stream_encode_plain;
    codec->dec = base64_stream_decode_plain;
    return true;
}

static bool
codec_choose_arm (struct codec *codec)
{
	(void)codec;
	return false;
}

static bool
codec_choose_x86 (struct codec *codec)
{
	(void)codec;
	return false;
}

void
codec_choose (struct codec *codec, int flags)
{
	// User forced a codec:
	if (codec_choose_forced(codec, flags)) {
		return;
	}

	// Runtime feature detection:
	if (codec_choose_arm(codec)) {
		return;
	}
	if (codec_choose_x86(codec)) {
		return;
	}
	codec->enc = base64_stream_encode_plain;
	codec->dec = base64_stream_decode_plain;
}