From 6b547899a8ba7c34556708f9736af1d8abbbe702 Mon Sep 17 00:00:00 2001
From: Vicki Pfau <vi@endrift.com>
Date: Mon, 24 Apr 2017 12:10:31 -0700
Subject: [PATCH] VFS: Add VFileFIFO for operating on circle buffers

---
 CHANGES                 |   1 +
 CMakeLists.txt          |   2 +-
 include/mgba-util/vfs.h |   3 ++
 src/util/vfs/vfs-fifo.c | 102 ++++++++++++++++++++++++++++++++++++++++
 4 files changed, 107 insertions(+), 1 deletion(-)
 create mode 100644 src/util/vfs/vfs-fifo.c

diff --git a/CHANGES b/CHANGES
index c7f1702fe..2598f6fcb 100644
--- a/CHANGES
+++ b/CHANGES
@@ -106,6 +106,7 @@ Misc:
  - Core: Ability to enumerate and modify video and audio channels
  - Debugger: Make attaching a backend idempotent
  - VFS: Optimize expanding in-memory files
+ - VFS: Add VFileFIFO for operating on circle buffers
 
 0.5.2: (2016-12-31)
 Bugfixes:
diff --git a/CMakeLists.txt b/CMakeLists.txt
index e5490a04b..c75114dc3 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -60,7 +60,7 @@ file(GLOB GB_RENDERER_SRC ${CMAKE_CURRENT_SOURCE_DIR}/src/gb/renderers/*.c)
 file(GLOB GB_EXTRA_SRC ${CMAKE_CURRENT_SOURCE_DIR}/src/gb/extra/*.c)
 file(GLOB THIRD_PARTY_SRC ${CMAKE_CURRENT_SOURCE_DIR}/src/third-party/inih/*.c)
 file(GLOB EXTRA_SRC ${CMAKE_CURRENT_SOURCE_DIR}/src/feature/*.c)
-set(CORE_VFS_SRC ${CMAKE_CURRENT_SOURCE_DIR}/src/util/vfs/vfs-mem.c)
+set(CORE_VFS_SRC ${CMAKE_CURRENT_SOURCE_DIR}/src/util/vfs/vfs-mem.c ${CMAKE_CURRENT_SOURCE_DIR}/src/util/vfs/vfs-fifo.c)
 set(VFS_SRC)
 source_group("ARM core" FILES ${ARM_SRC})
 source_group("LR35902 core" FILES ${LR35902_SRC})
diff --git a/include/mgba-util/vfs.h b/include/mgba-util/vfs.h
index 02c6d94e1..562fa52b5 100644
--- a/include/mgba-util/vfs.h
+++ b/include/mgba-util/vfs.h
@@ -73,6 +73,9 @@ struct VFile* VFileFromMemory(void* mem, size_t size);
 struct VFile* VFileFromConstMemory(const void* mem, size_t size);
 struct VFile* VFileMemChunk(const void* mem, size_t size);
 
+struct CircleBuffer;
+struct VFile* VFileFIFO(struct CircleBuffer* backing);
+
 struct VDir* VDirOpen(const char* path);
 struct VDir* VDirOpenArchive(const char* path);
 
diff --git a/src/util/vfs/vfs-fifo.c b/src/util/vfs/vfs-fifo.c
new file mode 100644
index 000000000..efff7bdab
--- /dev/null
+++ b/src/util/vfs/vfs-fifo.c
@@ -0,0 +1,102 @@
+/* Copyright (c) 2013-2017 Jeffrey Pfau
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#include <mgba-util/vfs.h>
+#include <mgba-util/circle-buffer.h>
+
+struct VFileFIFO {
+	struct VFile d;
+	struct CircleBuffer* backing;
+};
+
+static bool _vffClose(struct VFile* vf);
+static off_t _vffSeek(struct VFile* vf, off_t offset, int whence);
+static ssize_t _vffRead(struct VFile* vf, void* buffer, size_t size);
+static ssize_t _vffWrite(struct VFile* vf, const void* buffer, size_t size);
+static void* _vffMap(struct VFile* vf, size_t size, int flags);
+static void _vffUnmap(struct VFile* vf, void* memory, size_t size);
+static void _vffTruncate(struct VFile* vf, size_t size);
+static ssize_t _vffSize(struct VFile* vf);
+static bool _vffSync(struct VFile* vf, const void* buffer, size_t size);
+
+struct VFile* VFileFIFO(struct CircleBuffer* backing) {
+	if (!backing) {
+		return NULL;
+	}
+
+	struct VFileFIFO* vff = malloc(sizeof(*vff));
+	if (!vff) {
+		return NULL;
+	}
+
+	vff->backing = backing;
+	vff->d.close = _vffClose;
+	vff->d.seek = _vffSeek;
+	vff->d.read = _vffRead;
+	vff->d.readline = VFileReadline;
+	vff->d.write = _vffWrite;
+	vff->d.map = _vffMap;
+	vff->d.unmap = _vffUnmap;
+	vff->d.truncate = _vffTruncate;
+	vff->d.size = _vffSize;
+	vff->d.sync = _vffSync;
+
+	return &vff->d;
+}
+
+
+static bool _vffClose(struct VFile* vf) {
+	free(vf);
+	return true;
+}
+
+static off_t _vffSeek(struct VFile* vf, off_t offset, int whence) {
+	UNUSED(vf);
+	UNUSED(offset);
+	UNUSED(whence);
+	return 0;
+}
+
+static ssize_t _vffRead(struct VFile* vf, void* buffer, size_t size) {
+	struct VFileFIFO* vff = (struct VFileFIFO*) vf;
+	return CircleBufferRead(vff->backing, buffer, size);
+}
+
+static ssize_t _vffWrite(struct VFile* vf, const void* buffer, size_t size) {
+	struct VFileFIFO* vff = (struct VFileFIFO*) vf;
+	return CircleBufferWrite(vff->backing, buffer, size);
+}
+
+static void* _vffMap(struct VFile* vf, size_t size, int flags) {
+	UNUSED(vf);
+	UNUSED(size);
+	UNUSED(flags);
+	return NULL;
+}
+
+static void _vffUnmap(struct VFile* vf, void* memory, size_t size) {
+	UNUSED(vf);
+	UNUSED(memory);
+	UNUSED(size);
+}
+
+static void _vffTruncate(struct VFile* vf, size_t size) {
+	struct VFileFIFO* vff = (struct VFileFIFO*) vf;
+	if (!size) {
+		CircleBufferClear(vff->backing);
+	}
+}
+
+static ssize_t _vffSize(struct VFile* vf) {
+	struct VFileFIFO* vff = (struct VFileFIFO*) vf;
+	return CircleBufferSize(vff->backing);
+}
+
+static bool _vffSync(struct VFile* vf, const void* buffer, size_t size) {
+	UNUSED(vf);
+	UNUSED(buffer);
+	UNUSED(size);
+	return true;
+}