Add a method to get the system's page size

CMakeLists.txt

@@ -499,6 +499,7 @@ IF(HAVE_INTRIN_H)
         }" HAVE_CPUID_INTRINSIC)
 ENDIF()
 
+CHECK_SYMBOL_EXISTS(sysconf          unistd.h HAVE_SYSCONF)
 CHECK_SYMBOL_EXISTS(aligned_alloc    stdlib.h HAVE_ALIGNED_ALLOC)
 CHECK_SYMBOL_EXISTS(posix_memalign   stdlib.h HAVE_POSIX_MEMALIGN)
 CHECK_SYMBOL_EXISTS(_aligned_malloc  malloc.h HAVE__ALIGNED_MALLOC)

common/almalloc.c

@@ -10,8 +10,20 @@
 #endif
 #ifdef HAVE_WINDOWS_H
 #include <windows.h>
+#else
+#include <unistd.h>
 #endif
 
+
+#ifdef __GNUC__
+#define LIKELY(x) __builtin_expect(!!(x), !0)
+#define UNLIKELY(x) __builtin_expect(!!(x), 0)
+#else
+#define LIKELY(x) (!!(x))
+#define UNLIKELY(x) (!!(x))
+#endif
+
+
 void *al_malloc(size_t alignment, size_t size)
 {
 #if defined(HAVE_ALIGNED_ALLOC)
@@ -60,3 +72,39 @@ void al_free(void *ptr)
     }
 #endif
 }
+
+size_t al_get_page_size(void)
+{
+    static size_t psize = 0;
+    if(UNLIKELY(!psize))
+    {
+#ifdef HAVE_SYSCONF
+#if defined(_SC_PAGESIZE)
+        if(!psize) psize = sysconf(_SC_PAGESIZE);
+#elif defined(_SC_PAGE_SIZE)
+        if(!psize) psize = sysconf(_SC_PAGE_SIZE);
+#endif
+#endif /* HAVE_SYSCONF */
+#ifdef _WIN32
+        if(!psize)
+        {
+            SYSTEM_INFO sysinfo;
+            memset(&sysinfo, 0, sizeof(sysinfo));
+
+            GetSystemInfo(&sysinfo);
+            psize = sysinfo.dwPageSize;
+        }
+#endif
+        if(!psize) psize = DEF_ALIGN;
+    }
+    return psize;
+}
+
+int al_is_sane_alignment_allocator(void)
+{
+#if defined(HAVE_ALIGNED_ALLOC) || defined(HAVE_POSIX_MEMALIGN) || defined(HAVE__ALIGNED_MALLOC)
+    return 1;
+#else
+    return 0;
+#endif
+}

common/almalloc.h

@@ -14,6 +14,15 @@ void *al_malloc(size_t alignment, size_t size);
 void *al_calloc(size_t alignment, size_t size);
 void al_free(void *ptr);
 
+size_t al_get_page_size(void);
+
+/**
+ * Returns non-0 if the allocation function has direct alignment handling.
+ * Otherwise, the standard malloc is used with an over-allocation and pointer
+ * offset strategy.
+ */
+int al_is_sane_alignment_allocator(void);
+
 #ifdef __cplusplus
 }
 #endif

config.h.in

@@ -11,6 +11,9 @@
 /* Define if HRTF data is embedded in the library */
 #cmakedefine ALSOFT_EMBED_HRTF_DATA
 
+/* Define if we have the sysconf function */
+#cmakedefine HAVE_SYSCONF
+
 /* Define if we have the C11 aligned_alloc function */
 #cmakedefine HAVE_ALIGNED_ALLOC