84 lines
2.2 KiB
C
84 lines
2.2 KiB
C
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/*
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* Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include <stdlib.h>
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#include <string.h>
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#include <features.h>
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#if __GLIBC_PREREQ(2, 16)
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#include <sys/auxv.h>
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#else
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#include <fcntl.h>
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#include <unistd.h>
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#include <errno.h>
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#include <link.h>
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#endif
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#include "webrtc/system_wrappers/include/cpu_features_wrapper.h"
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#if defined(WEBRTC_ARCH_ARM_FAMILY)
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#include <asm/hwcap.h>
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uint64_t WebRtc_GetCPUFeaturesARM(void) {
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uint64_t result = 0;
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int architecture = 0;
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unsigned long hwcap = 0;
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const char* platform = NULL;
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#if __GLIBC_PREREQ(2, 16)
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hwcap = getauxval(AT_HWCAP);
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platform = (const char*)getauxval(AT_PLATFORM);
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#else
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ElfW(auxv_t) auxv;
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int fd = open("/proc/self/auxv", O_RDONLY);
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if (fd >= 0) {
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while (hwcap == 0 || platform == NULL) {
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if (read(fd, &auxv, sizeof(auxv)) < (ssize_t)sizeof(auxv)) {
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if (errno == EINTR)
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continue;
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break;
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}
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switch (auxv.a_type) {
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case AT_HWCAP:
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hwcap = auxv.a_un.a_val;
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break;
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case AT_PLATFORM:
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platform = (const char*)auxv.a_un.a_val;
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break;
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}
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}
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close(fd);
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}
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#endif // __GLIBC_PREREQ(2,16)
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#if defined(__aarch64__)
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architecture = 8;
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if ((hwcap & HWCAP_FP) != 0)
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result |= kCPUFeatureVFPv3;
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if ((hwcap & HWCAP_ASIMD) != 0)
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result |= kCPUFeatureNEON;
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#else
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if (platform != NULL) {
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/* expect a string in the form "v6l" or "v7l", etc.
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*/
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if (platform[0] == 'v' && '0' <= platform[1] && platform[1] <= '9' &&
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(platform[2] == 'l' || platform[2] == 'b')) {
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architecture = platform[1] - '0';
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}
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}
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if ((hwcap & HWCAP_VFPv3) != 0)
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result |= kCPUFeatureVFPv3;
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if ((hwcap & HWCAP_NEON) != 0)
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result |= kCPUFeatureNEON;
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#endif
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if (architecture >= 7)
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result |= kCPUFeatureARMv7;
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if (architecture >= 6)
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result |= kCPUFeatureLDREXSTREX;
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return result;
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}
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#endif // WEBRTC_ARCH_ARM_FAMILY
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