Add custom allocator support

1 files changed, 152 insertions, 0 deletions

diff --git a/include/zix/allocator.h b/include/zix/allocator.h
new file mode 100644
index 0000000..73e2207
--- /dev/null
+++ b/include/zix/allocator.h
@@ -0,0 +1,152 @@
+/*
+  Copyright 2021 David Robillard <d@drobilla.net>
+
+  Permission to use, copy, modify, and/or distribute this software for any
+  purpose with or without fee is hereby granted, provided that the above
+  copyright notice and this permission notice appear in all copies.
+
+  THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+
+#ifndef ZIX_ALLOCATOR_H
+#define ZIX_ALLOCATOR_H
+
+#include "zix/attributes.h"
+
+#include <stddef.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+   @addtogroup zix
+   @{
+   @name Allocator
+   @{
+*/
+
+/// Opaque user data for allocation functions
+typedef void ZixAllocatorHandle;
+
+/**
+   General malloc-like memory allocation function.
+
+   This works like the standard C malloc(), except has an additional handle
+   parameter for implementing stateful allocators without static data.
+*/
+typedef void* ZIX_ALLOCATED (
+  *ZixMallocFunc)(ZixAllocatorHandle* ZIX_NULLABLE handle, size_t size);
+
+/**
+   General calloc-like memory allocation function.
+
+   This works like the standard C calloc(), except has an additional handle
+   parameter for implementing stateful allocators without static data.
+*/
+typedef void* ZIX_ALLOCATED (*ZixCallocFunc)(ZixAllocatorHandle* ZIX_NULLABLE
+                                                    handle,
+                                             size_t nmemb,
+                                             size_t size);
+
+/**
+   General realloc-like memory reallocation function.
+
+   This works like the standard C remalloc(), except has an additional handle
+   parameter for implementing stateful allocators without static data.
+*/
+typedef void* ZIX_ALLOCATED (*ZixReallocFunc)(ZixAllocatorHandle* ZIX_NULLABLE
+                                                                 handle,
+                                              void* ZIX_NULLABLE ptr,
+                                              size_t             size);
+
+/**
+   General free-like memory deallocation function.
+
+   This works like the standard C remalloc(), except has an additional handle
+   parameter for implementing stateful allocators without static data.
+*/
+typedef void (*ZixFreeFunc)(ZixAllocatorHandle* ZIX_NULLABLE handle,
+                            void* ZIX_NULLABLE               ptr);
+
+/**
+   A memory allocator.
+
+   This object-like structure provides an interface like the standard C
+   functions malloc(), calloc(), realloc(), and free().  It allows the user to
+   pass a custom allocator to be used by data structures.
+*/
+typedef struct {
+  ZixAllocatorHandle* ZIX_NULLABLE handle;
+  ZixMallocFunc ZIX_NONNULL        malloc;
+  ZixCallocFunc ZIX_NONNULL        calloc;
+  ZixReallocFunc ZIX_NONNULL       realloc;
+  ZixFreeFunc ZIX_NONNULL          free;
+} ZixAllocator;
+
+/// Return the default allocator which simply uses the system allocator
+ZIX_CONST_API
+const ZixAllocator* ZIX_NONNULL
+zix_default_allocator(void);
+
+/// Convenience wrapper that defers to malloc() if allocator is null
+static inline void* ZIX_ALLOCATED
+zix_malloc(const ZixAllocator* const ZIX_NULLABLE allocator, const size_t size)
+{
+  const ZixAllocator* const actual =
+    allocator ? allocator : zix_default_allocator();
+
+  return actual->malloc(actual->handle, size);
+}
+
+/// Convenience wrapper that defers to calloc() if allocator is null
+static inline void* ZIX_ALLOCATED
+zix_calloc(const ZixAllocator* const ZIX_NULLABLE allocator,
+           const size_t                           nmemb,
+           const size_t                           size)
+{
+  const ZixAllocator* const actual =
+    allocator ? allocator : zix_default_allocator();
+
+  return actual->calloc(actual->handle, nmemb, size);
+}
+
+/// Convenience wrapper that defers to realloc() if allocator is null
+static inline void* ZIX_ALLOCATED
+zix_realloc(const ZixAllocator* const ZIX_NULLABLE allocator,
+            void* const ZIX_NULLABLE               ptr,
+            const size_t                           size)
+{
+  const ZixAllocator* const actual =
+    allocator ? allocator : zix_default_allocator();
+
+  return actual->realloc(actual->handle, ptr, size);
+}
+
+/// Convenience wrapper that defers to free() if allocator is null
+static inline void
+zix_free(const ZixAllocator* const ZIX_NULLABLE allocator,
+         void* const ZIX_NULLABLE               ptr)
+{
+  const ZixAllocator* const actual =
+    allocator ? allocator : zix_default_allocator();
+
+  actual->free(actual->handle, ptr);
+}
+
+/**
+   @}
+   @}
+*/
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+#endif /* ZIX_ALLOCATOR_H */