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Diffstat (limited to '')
| -rw-r--r-- | mozglue/build/arm.cpp | 131 |
1 files changed, 131 insertions, 0 deletions
diff --git a/mozglue/build/arm.cpp b/mozglue/build/arm.cpp new file mode 100644 index 0000000000..a74a41f6c0 --- /dev/null +++ b/mozglue/build/arm.cpp @@ -0,0 +1,131 @@ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +/* compile-time and runtime tests for whether to use various ARM extensions */ + +#include "arm.h" + +#if defined(MOZILLA_ARM_HAVE_CPUID_DETECTION) + +// arm.h has parallel #ifs which declare MOZILLA_ARM_HAVE_CPUID_DETECTION. +// We don't check it here so that we get compile errors if it's defined, but +// we don't compile one of these detection methods. The detection code here is +// based on the CPU detection in libtheora. + +# if defined(__linux__) || defined(ANDROID) +# include <stdio.h> +# include <stdlib.h> +# include <string.h> + +enum { + MOZILLA_HAS_EDSP_FLAG = 1, + MOZILLA_HAS_ARMV6_FLAG = 2, + MOZILLA_HAS_ARMV7_FLAG = 4, + MOZILLA_HAS_NEON_FLAG = 8 +}; + +static unsigned get_arm_cpu_flags(void) { + unsigned flags; + FILE* fin; + bool armv6_processor = false; + flags = 0; + /*Reading /proc/self/auxv would be easier, but that doesn't work reliably on + Android. This also means that detection will fail in Scratchbox, which is + desirable, as NEON does not work in the qemu shipped with the Maemo 5 SDK. + I don't know if /proc/self/auxv would do any better in that case, anyway, + or if it would return random flags from the host CPU.*/ + fin = fopen("/proc/cpuinfo", "r"); + if (fin != nullptr) { + /*512 should be enough for anybody (it's even enough for all the flags that + x86 has accumulated... so far).*/ + char buf[512]; + while (fgets(buf, 511, fin) != nullptr) { + if (memcmp(buf, "Features", 8) == 0) { + char* p; + p = strstr(buf, " edsp"); + if (p != nullptr && (p[5] == ' ' || p[5] == '\n')) + flags |= MOZILLA_HAS_EDSP_FLAG; + p = strstr(buf, " neon"); + if (p != nullptr && (p[5] == ' ' || p[5] == '\n')) + flags |= MOZILLA_HAS_NEON_FLAG; + } + if (memcmp(buf, "CPU architecture:", 17) == 0) { + int version; + version = atoi(buf + 17); + if (version >= 6) flags |= MOZILLA_HAS_ARMV6_FLAG; + if (version >= 7) flags |= MOZILLA_HAS_ARMV7_FLAG; + } + /* media/webrtc/trunk/src/system_wrappers/source/cpu_features_arm.c + * Unfortunately, it seems that certain ARMv6-based CPUs + * report an incorrect architecture number of 7! + * + * We try to correct this by looking at the 'elf_format' + * field reported by the 'Processor' field, which is of the + * form of "(v7l)" for an ARMv7-based CPU, and "(v6l)" for + * an ARMv6-one. + */ + if (memcmp(buf, "Processor\t:", 11) == 0) { + if (strstr(buf, "(v6l)") != 0) { + armv6_processor = true; + } + } + } + fclose(fin); + } + if (armv6_processor) { + // ARMv6 pretending to be ARMv7? clear flag + if (flags & MOZILLA_HAS_ARMV7_FLAG) { + flags &= ~MOZILLA_HAS_ARMV7_FLAG; + } + } + return flags; +} + +// Cache a local copy so we only have to read /proc/cpuinfo once. +static unsigned arm_cpu_flags = get_arm_cpu_flags(); + +# if !defined(MOZILLA_PRESUME_EDSP) +static bool check_edsp(void) { + return (arm_cpu_flags & MOZILLA_HAS_EDSP_FLAG) != 0; +} +# endif + +# if !defined(MOZILLA_PRESUME_ARMV6) +static bool check_armv6(void) { + return (arm_cpu_flags & MOZILLA_HAS_ARMV6_FLAG) != 0; +} +# endif + +# if !defined(MOZILLA_PRESUME_ARMV7) +static bool check_armv7(void) { + return (arm_cpu_flags & MOZILLA_HAS_ARMV7_FLAG) != 0; +} +# endif + +# if !defined(MOZILLA_PRESUME_NEON) +static bool check_neon(void) { + return (arm_cpu_flags & MOZILLA_HAS_NEON_FLAG) != 0; +} +# endif + +# endif // defined(__linux__) || defined(ANDROID) + +namespace mozilla { +namespace arm_private { +# if !defined(MOZILLA_PRESUME_EDSP) +bool edsp_enabled = check_edsp(); +# endif +# if !defined(MOZILLA_PRESUME_ARMV6) +bool armv6_enabled = check_armv6(); +# endif +# if !defined(MOZILLA_PRESUME_ARMV7) +bool armv7_enabled = check_armv7(); +# endif +# if !defined(MOZILLA_PRESUME_NEON) +bool neon_enabled = check_neon(); +# endif +} // namespace arm_private +} // namespace mozilla + +#endif // MOZILLA_ARM_HAVE_CPUID_DETECTION |