1 files changed, 91 insertions, 0 deletions
diff --git a/pal/posix.h b/pal/posix.h
new file mode 100755
index 0000000..8ac9775
--- /dev/null
+++ b/pal/posix.h
@@ -0,0 +1,91 @@
+#pragma once
+
+#include <iostream>
+#include <sys/mman.h>
+#include <sys/resource.h>
+
+#define DECL_MAIN int main()
+
+#define NOINLINE __attribute__((noinline))
+
+namespace pal {
+
+static constexpr size_t kPageSize =
+    #if defined(__APPLE__) && defined(__aarch64__)
+        0x4000
+    #else
+        0x1000
+    #endif
+    ;
+
+inline void* MemReserve(size_t len) {
+    int flags = MAP_PRIVATE | MAP_ANONYMOUS;
+
+    #ifdef MAP_NORESERVE
+        // On Linux, guarantee lazy commit even if /proc/sys/vm/overcommit_memory is set to `heuristic` (0).
+        flags |= MAP_NORESERVE;
+    #endif
+
+    void* buf = mmap(nullptr, len, PROT_NONE, flags, -1, 0);
+    if (buf == nullptr) {
+        int saved_errno = errno;
+        std::cerr << "Reserving memory with mmap failed. Exit code: " << saved_errno << std::endl;
+        return nullptr;
+    }
+
+    return buf;
+}
+
+inline bool MemCommit(void* p, size_t len) {
+    if (mprotect(p, len, PROT_READ | PROT_WRITE) != 0) {
+        int saved_errno = errno;
+        std::cerr << "Committing memory with mprotect failed. Exit code: " << saved_errno << std::endl;
+        return false;
+    }
+
+    return true;
+}
+
+inline void MemFree(void* p, size_t len) {
+    if (munmap(p, len) != 0) {
+        int saved_errno = errno;
+        std::cerr << "Failed to unmap memory. Exit code: " << saved_errno << std::endl;
+    }
+}
+
+inline size_t GetPeakMemoryUse() {
+    rusage r_usage;
+    if (getrusage(RUSAGE_SELF, &r_usage) != 0) {
+        int saved_errno = errno;
+        std::cerr << "Failed to fetch memory use. Exit code: " << saved_errno << std::endl;
+        return 0;
+    }
+
+    // On Mac, ru_maxrss is in bytes. On Linux and FreeBSD it's in kilobytes. So much for POSIX.
+    #ifdef __APPLE__
+    size_t multiplier = 1;
+    #else
+    size_t multiplier = 1000;
+    #endif
+
+    return r_usage.ru_maxrss * multiplier;
+}
+
+inline uint64_t ConvertTimevalToMicroseconds(timeval t) {
+    return static_cast<uint64_t>(t.tv_sec) * 1000000ULL + static_cast<uint64_t>(t.tv_usec);
+}
+
+inline uint64_t GetCpuTime() {
+    rusage r_usage;
+    if (getrusage(RUSAGE_SELF, &r_usage) != 0) {
+        int saved_errno = errno;
+        std::cerr << "Failed to fetch memory use. Exit code: " << saved_errno << std::endl;
+        return 0;
+    }
+
+    auto user_time = ConvertTimevalToMicroseconds(r_usage.ru_utime);
+    auto kernel_time = ConvertTimevalToMicroseconds(r_usage.ru_stime);
+    return user_time + kernel_time;
+}
+
+} // namespace pal