ref: 4d8958d8dddb9104e006bc806a2607bd4ee71708
dir: /vpx_ports/ppc_cpudetect.c/
/* * Copyright (c) 2017 The WebM project authors. All Rights Reserved. * * Use of this source code is governed by a BSD-style license * that can be found in the LICENSE file in the root of the source * tree. An additional intellectual property rights grant can be found * in the file PATENTS. All contributing project authors may * be found in the AUTHORS file in the root of the source tree. */ #include <fcntl.h> #include <unistd.h> #include <stdint.h> #include <asm/cputable.h> #include <linux/auxvec.h> #include "./vpx_config.h" #include "vpx_ports/ppc.h" #if CONFIG_RUNTIME_CPU_DETECT static int cpu_env_flags(int *flags) { char *env; env = getenv("VPX_SIMD_CAPS"); if (env && *env) { *flags = (int)strtol(env, NULL, 0); return 0; } *flags = 0; return -1; } static int cpu_env_mask(void) { char *env; env = getenv("VPX_SIMD_CAPS_MASK"); return env && *env ? (int)strtol(env, NULL, 0) : ~0; } int ppc_simd_caps(void) { int flags; int mask; int fd; ssize_t count; unsigned int i; uint64_t buf[64]; // If VPX_SIMD_CAPS is set then allow only those capabilities. if (!cpu_env_flags(&flags)) { return flags; } mask = cpu_env_mask(); fd = open("/proc/self/auxv", O_RDONLY); if (fd < 0) { return 0; } while ((count = read(fd, buf, sizeof(buf))) > 0) { for (i = 0; i < (count / sizeof(*buf)); i += 2) { if (buf[i] == AT_HWCAP) { #if HAVE_VSX if (buf[i + 1] & PPC_FEATURE_HAS_VSX) { flags |= HAS_VSX; } #endif // HAVE_VSX goto out_close; } else if (buf[i] == AT_NULL) { goto out_close; } } } out_close: close(fd); return flags & mask; } #else // If there is no RTCD the function pointers are not used and can not be // changed. int ppc_simd_caps(void) { return 0; } #endif // CONFIG_RUNTIME_CPU_DETECT