More tests and documentation

Also, split out platform-specific parts and add mocks for tests.

1 files changed, 51 insertions, 0 deletions

diff --git a/src/allocator.h b/src/allocator.h
new file mode 100644
index 0000000..d89bd29
--- /dev/null
+++ b/src/allocator.h
@@ -0,0 +1,51 @@
+#include <stddef.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+/**
+ * Simple bump allocator that can be used for
+ * allocations with a frame lifetime.
+ */
+struct frame_allocator {
+  uint8_t *buf;
+  size_t offset;
+  size_t capacity;
+};
+
+/**
+ * Create a new frame allocator
+ *
+ * @param capacity The capacity in bytes of the frame allocator
+ * @returns The frame allocator
+ */
+struct frame_allocator frame_allocator_create(size_t capacity) {
+  return (struct frame_allocator){
+      .capacity = capacity, .offset = 0, .buf = (uint8_t *)malloc(capacity)};
+}
+
+/**
+ * Allocate memory in this @ref frame_allocator "frame allocator"
+ *
+ * @param alloc The allocator to allocate in
+ * @param sz The size in bytes to allocate.
+ * @returns void* representing the start of the allocated region on success,
+ * NULL on failure.
+ */
+void *frame_allocator_alloc(struct frame_allocator *alloc, size_t sz) {
+  if (alloc->offset + sz > alloc->capacity) {
+    return NULL;
+  }
+
+  void *mem = alloc->buf + alloc->offset;
+  alloc->offset += sz;
+
+  return mem;
+}
+
+/**
+ * Clear this @ref frame_allocator "frame allocator".
+ *
+ * This does not free any memory, but simply resets the offset to 0.
+ * @param alloc The frame allocator to clear
+ */
+void frame_allocator_clear(struct frame_allocator *alloc) { alloc->offset = 0; }