1 files changed, 117 insertions, 0 deletions
diff --git a/src/stack.h b/src/stack.h
new file mode 100644
index 00000000..e95c5770
--- /dev/null
+++ b/src/stack.h
@@ -0,0 +1,117 @@
+/*
+  Copyright 2011-2020 David Robillard <http://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 SERD_STACK_H
+#define SERD_STACK_H
+
+#include "serd_internal.h"
+
+#include <assert.h>
+#include <stddef.h>
+#include <stdlib.h>
+
+/** An offset to start the stack at. Note 0 is reserved for NULL. */
+#define SERD_STACK_BOTTOM sizeof(void*)
+
+/** A dynamic stack in memory. */
+typedef struct {
+	uint8_t* buf;       ///< Stack memory
+	size_t   buf_size;  ///< Allocated size of buf (>= size)
+	size_t   size;      ///< Conceptual size of stack in buf
+} SerdStack;
+
+/** An offset to start the stack at. Note 0 is reserved for NULL. */
+#define SERD_STACK_BOTTOM sizeof(void*)
+
+static inline SerdStack
+serd_stack_new(size_t size)
+{
+	SerdStack stack;
+	stack.buf       = (uint8_t*)calloc(size, 1);
+	stack.buf_size  = size;
+	stack.size      = SERD_STACK_BOTTOM;
+	return stack;
+}
+
+static inline bool
+serd_stack_is_empty(SerdStack* stack)
+{
+	return stack->size <= SERD_STACK_BOTTOM;
+}
+
+static inline void
+serd_stack_free(SerdStack* stack)
+{
+	free(stack->buf);
+	stack->buf      = NULL;
+	stack->buf_size = 0;
+	stack->size     = 0;
+}
+
+static inline uint8_t*
+serd_stack_push(SerdStack* stack, size_t n_bytes)
+{
+	const size_t new_size = stack->size + n_bytes;
+	if (stack->buf_size < new_size) {
+		stack->buf_size += (stack->buf_size >> 1); // *= 1.5
+		stack->buf = (uint8_t*)realloc(stack->buf, stack->buf_size);
+	}
+	uint8_t* const ret = (stack->buf + stack->size);
+	stack->size = new_size;
+	return ret;
+}
+
+static inline void
+serd_stack_pop(SerdStack* stack, size_t n_bytes)
+{
+	assert(stack->size >= n_bytes);
+	stack->size -= n_bytes;
+}
+
+static inline void*
+serd_stack_push_aligned(SerdStack* stack, size_t n_bytes, size_t align)
+{
+	// Push one byte to ensure space for a pad count
+	serd_stack_push(stack, 1);
+
+	// Push padding if necessary
+	const size_t pad = align - stack->size % align;
+	if (pad > 0) {
+		serd_stack_push(stack, pad);
+	}
+
+	// Set top of stack to pad count so we can properly pop later
+	assert(pad < UINT8_MAX);
+	stack->buf[stack->size - 1] = (uint8_t)pad;
+
+	// Push requested space at aligned location
+	return serd_stack_push(stack, n_bytes);
+}
+
+static inline void
+serd_stack_pop_aligned(SerdStack* stack, size_t n_bytes)
+{
+	// Pop requested space down to aligned location
+	serd_stack_pop(stack, n_bytes);
+
+	// Get amount of padding from top of stack
+	const uint8_t pad = stack->buf[stack->size - 1];
+
+	// Pop padding and pad count
+	serd_stack_pop(stack, pad + 1u);
+}
+
+#endif  // SERD_STACK_H