1 files changed, 359 insertions, 0 deletions

diff --git a/firmware/include/buflib.h b/firmware/include/buflib.h
index 36d171963a..32a5a6abe0 100644
--- a/firmware/include/buflib.h
+++ b/firmware/include/buflib.h
@@ -7,6 +7,8 @@
  *                     \/            \/     \/    \/            \/
  * $Id$
  *
+ * Copyright (C) 2009 Andrew Mahone
+ * Copyright (C) 2011 Thomas Martitz
  * Copyright (C) 2023 Aidan MacDonald
  *
  * This program is free software; you can redistribute it and/or
@@ -22,9 +24,366 @@
 #define _BUFLIB_H_
 
 #include "config.h"
+#include <stdint.h>
+#include <stdbool.h>
+#include <string.h>
+
+/* Add extra checks to buflib_get_data to catch bad handles */
+//#define BUFLIB_DEBUG_GET_DATA
+
+/* Support integrity check */
+//#define BUFLIB_DEBUG_CHECK_VALID
+
+/* Support debug printing of memory blocks */
+//#define BUFLIB_DEBUG_PRINT
+
+/* Defined by the backend header. */
+struct buflib_context;
+
+/* Buflib callback return codes. */
+#define BUFLIB_CB_OK            0
+#define BUFLIB_CB_CANNOT_MOVE   1
+#define BUFLIB_CB_CANNOT_SHRINK 1
+
+/* Buflib shrink hints. */
+#define BUFLIB_SHRINK_SIZE_MASK (~BUFLIB_SHRINK_POS_MASK)
+#define BUFLIB_SHRINK_POS_FRONT (1u<<31)
+#define BUFLIB_SHRINK_POS_BACK  (1u<<30)
+#define BUFLIB_SHRINK_POS_MASK  (BUFLIB_SHRINK_POS_FRONT|BUFLIB_SHRINK_POS_BACK)
+
+/**
+ * Callbacks run by buflib to manage an allocation.
+ */
+struct buflib_callbacks
+{
+    /**
+     * \brief Called when buflib wants to move the buffer
+     * \param handle    Handle being moved
+     * \param current   Current address of the buffer
+     * \param new       New address the buffer would have after moving
+     * \return BUFLIB_CB_OK - Allow the buffer to be moved.
+     * \return BUFLIB_CB_CANNOT_MOVE - Do not allow the buffer to be moved.
+     *
+     * This callback allows you to fix up any pointers that might
+     * be pointing to the buffer before it is moved. The task of
+     * actually moving the buffer contents is performed by buflib
+     * after the move callback returns, if movement is allowed.
+     *
+     * Care must be taken to ensure that the buffer is not accessed
+     * from outside the move callback until the move is complete. If
+     * this is a concern, eg. due to multi-threaded access, then you
+     * must implement a sync_callback() and guard any access to the
+     * buffer with a lock.
+     *
+     * If the move callback is NULL then buflib will never move
+     * the allocation, as if you returned BUFLIB_CB_CANNOT_MOVE.
+     */
+    int (*move_callback)(int handle, void* current, void* new);
+
+    /**
+     * \brief Called when buflib wants to shrink the buffer
+     * \param handle    Handle to shrink
+     * \param hints     Hints regarding the shrink request
+     * \param start     Current address of the buffer
+     * \param size      Current size of the buffer as seen by buflib.
+     *                  This may be rounded up compared to the nominal
+     *                  allocation size due to alignment requirements.
+     * \return BUFLIB_CB_OK - Was able to shrink the buffer.
+     * \return BUFLIB_CB_CANNOT_SHRINK - Buffer cannot shrink.
+     *
+     * This callback is run by buflib when it runs out of memory
+     * and starts a compaction run. Buflib will not actually try
+     * to shrink or move memory, you must do that yourself and
+     * call buflib_shrink() to report the new start address and
+     * size of the buffer.
+     *
+     * If the shrink callback is NULL then buflib will regard the
+     * buffer as non-shrinkable.
+     */
+    int (*shrink_callback)(int handle, unsigned hints,
+                           void *start, size_t size);
+
+    /**
+     * \brief Called before and after attempting to move the buffer
+     * \param handle    Handle being moved
+     * \param lock      True to lock, false to unlock
+     *
+     * The purpose of this callback is to block access to the buffer
+     * from other threads while a buffer is being moved, using a lock
+     * such as a mutex.
+     *
+     * It is called with `sync_callback(handle, true)` before running
+     * the move callback and `sync_callback(handle, false)` after the
+     * move is complete, regardless of whether the buffer was actually
+     * moved or not.
+     */
+    void (*sync_callback)(int handle, bool lock);
+};
+
+/**
+ * A set of all NULL callbacks for use with allocations that need to stay
+ * locked in RAM and not moved or shrunk. These type of allocations should
+ * be avoided as much as possible to avoid memory fragmentation but it can
+ * suitable for short-lived allocations.
+ *
+ * \note Use of this is discouraged. Prefer to use normal moveable
+ *       allocations and pin them.
+ */
+extern struct buflib_callbacks buflib_ops_locked;
+
+/**
+ * \brief Intialize a buflib context
+ * \param ctx       Context to initialize
+ * \param buf       Buffer which will be used as the context's memory pool
+ * \param size      Size of the buffer
+ */
+void buflib_init(struct buflib_context *ctx, void *buf, size_t size);
+
+/**
+ * Returns the amount of unallocated bytes. It does not mean this amount
+ * can be actually allocated because they might not be contiguous.
+ */
+size_t buflib_available(struct buflib_context *ctx);
+
+/**
+ * Returns the size of the largest possible contiguous allocation, given
+ * the current state of the memory pool. A larger allocation may still
+ * succeed if compaction is able to create a larger contiguous area.
+ */
+size_t buflib_allocatable(struct buflib_context *ctx);
+
+/**
+ * \brief Relocate the buflib memory pool to a new address
+ * \param ctx       Context to relocate
+ * \param buf       New memory pool address
+ * \return True if relocation should proceed, false if it cannot.
+ *
+ * Updates all pointers inside the buflib context to point to a new pool
+ * address. You must call this function before moving the pool and move
+ * the data manually afterwards only if this function returns true.
+ *
+ * This is intended from a move_callback() in buflib-on-buflib scenarios,
+ * where the memory pool of the "inner" buflib is allocated from an "outer"
+ * buflib.
+ *
+ * \warning This does not run any move callbacks, so it is not safe to
+ *          use if any allocations require them.
+ */
+bool buflib_context_relocate(struct buflib_context *ctx, void *buf);
+
+/**
+ * \brief Allocate memory from buflib
+ * \param ctx       Context to allocate from
+ * \param size      Allocation size
+ * \return Handle for the allocation (> 0) or a negative value on error
+ *
+ * This is the same as calling buflib_alloc_ex() with a NULL callbacks
+ * struct. The resulting allocation can be moved by buflib; use pinning
+ * if you need to prevent moves.
+ *
+ * Note that zero is not a valid handle, and will never be returned by
+ * this function. However, this may change, and you should treat a zero
+ * or negative return value as an allocation failure.
+ */
+int buflib_alloc(struct buflib_context *ctx, size_t size);
+
+/**
+ * \brief Allocate memory from buflib with custom buffer ops
+ * \param ctx       Context to allocate from
+ * \param size      Allocation size
+ * \param ops       Pointer to ops struct or NULL if no ops are needed.
+ * \return Handle for the allocation (> 0) or a negative value on error.
+ *
+ * Use this if you need to pass custom callbacks for responding to buflib
+ * move or shrink operations. Passing a NULL ops pointer means the buffer
+ * can be moved by buflib at any time.
+ *
+ * Note that zero is not a valid handle, and will never be returned by
+ * this function. However, this may change, and you should treat a zero
+ * or negative return value as an allocation failure.
+ */
+int buflib_alloc_ex(struct buflib_context *ctx, size_t size,
+                    struct buflib_callbacks *ops);
+
+/**
+ * \brief Attempt a maximum size allocation
+ * \param ctx       Context to allocate from
+ * \param size      Size of the allocation will be written here on success.
+ * \param ops       Pointer to ops struct or NULL if no ops are needed.
+ * \return Handle for the allocation (> 0) or a negative value on error.
+ *
+ * Buflib will attempt to compact and shrink other allocations as much as
+ * possible and then allocate the largest contigous free area. Since this
+ * will consume effectively *all* available memory, future allocations are
+ * likely to fail.
+ *
+ * \note There is rarely any justification to use this with the core_alloc
+ *       context due to the impact it has on the entire system. You should
+ *       change your code if you think you need this. Of course, if you are
+ *       using a private buflib context then this warning does not apply.
+ */
+int buflib_alloc_maximum(struct buflib_context *ctx,
+                         size_t *size, struct buflib_callbacks *ops);
+
+/**
+ * \brief Reduce the size of a buflib allocation
+ * \param ctx       Buflib context of the allocation
+ * \param handle    Handle identifying the allocation
+ * \param newstart  New start address. Must be within the current bounds
+ *                  of the allocation, as returned by buflib_get_data().
+ * \param new_size  New size of the buffer.
+ * \return True if shrinking was successful; otherwise, returns false and
+ *         does not modify the allocation.
+ *
+ * Shrinking always succeeds provided the new allocation is contained
+ * within the current allocation. A failure is always a programming
+ * error, so you need not check for it and in the future the failure
+ * case may be changed to a panic or undefined behavior with no return
+ * code.
+ *
+ * The new start address and size need not have any particular alignment,
+ * however buflib cannot work with unaligned addresses so there is rarely
+ * any purpose to creating unaligned allocations.
+ *
+ * Shrinking is typically done from a shrink_callback(), but can be done
+ * at any time if you want to reduce the size of a buflib allocation.
+ */
+bool buflib_shrink(struct buflib_context *ctx, int handle,
+                   void *newstart, size_t new_size);
+
+/**
+ * \brief Increment an allocation's pin count
+ * \param ctx       Buflib context of the allocation
+ * \param handle    Handle identifying the allocation
+ *
+ * The pin count acts like a reference count. Buflib will not attempt to
+ * move any buffer with a positive pin count, nor invoke any move or sync
+ * callbacks. Hence, when pinned, it is safe to hold pointers to a buffer
+ * across yields or use them for I/O.
+ *
+ * Note that shrink callbacks can still be invoked for pinned handles.
+ */
+void buflib_pin(struct buflib_context *ctx, int handle);
+
+/**
+ * \brief Decrement an allocation's pin count
+ * \param ctx       Buflib context of the allocation
+ * \param handle    Handle identifying the allocation
+ */
+void buflib_unpin(struct buflib_context *ctx, int handle);
+
+/**
+ * \brief Return the pin count of an allocation
+ * \param ctx       Buflib context of the allocation
+ * \param handle    Handle identifying the allocation
+ * \return Current pin count; zero means the handle is not pinned.
+ */
+unsigned buflib_pin_count(struct buflib_context *ctx, int handle);
+
+/**
+ * \brief Free an allocation and return its memory to the pool
+ * \param ctx       Buflib context of the allocation
+ * \param handle    Handle identifying the allocation
+ * \return Always returns zero (zero is not a valid handle, so this can
+ *         be used to invalidate the variable containing the handle).
+ */
+int buflib_free(struct buflib_context *context, int handle);
+
+/**
+ * \brief Get a pointer to the buffer for an allocation
+ * \param ctx       Buflib context of the allocation
+ * \param handle    Handle identifying the allocation
+ * \return Pointer to the allocation's memory.
+ *
+ * Note that buflib can move allocations in order to free up space when
+ * making new allocations. For this reason, it's unsafe to hold a pointer
+ * to a buffer across a yield() or any other operation that can cause a
+ * context switch. This includes any function that may block, and even
+ * some functions that might not block -- eg. if a low priority thread
+ * acquires a mutex, calling mutex_unlock() may trigger a context switch
+ * to a higher-priority thread.
+ *
+ * buflib_get_data() is a very cheap operation, however, costing only
+ * a few pointer lookups. Don't hesitate to use it extensively.
+ *
+ * If you need to hold a pointer across a possible context switch, pin
+ * the handle with buflib_pin() to prevent the buffer from being moved.
+ * This is required when doing I/O into buflib allocations, for example.
+ */
+#ifdef BUFLIB_DEBUG_GET_DATA
+void *buflib_get_data(struct buflib_context *ctx, int handle);
+#else
+static inline void *buflib_get_data(struct buflib_context *ctx, int handle);
+#endif
+
+/**
+ * \brief Shift allocations up to free space at the start of the pool
+ * \param ctx       Context to operate on
+ * \param size      Indicates number of bytes to free up, or 0 to free
+ *                  up as much as possible. On return, the actual number
+ *                  of bytes freed is written here.
+ * \return Pointer to the start of the free area
+ *
+ * If `*size` is non-zero, the actual amount of space freed up might
+ * be less than `*size`.
+ *
+ * \warning This will move data around in the pool without calling any
+ *          move callbacks!
+ * \warning This function is deprecated and will eventually be removed.
+ */
+void* buflib_buffer_out(struct buflib_context *ctx, size_t *size);
+
+/**
+ * \brief Shift allocations down into free space below the pool
+ * \param ctx       Context to operate on
+ * \param size      Number of bytes to add to the pool.
+ *
+ * This operation should only be used to return memory that was previously
+ * taken from the pool with buflib_buffer_out(), by passing the same size
+ * that you got from that function.
+ *
+ * \warning This will move data around in the pool without calling any
+ *          move callbacks!
+ * \warning This function is deprecated and will eventually be removed.
+ */
+void buflib_buffer_in(struct buflib_context *ctx, int size);
+
+#ifdef BUFLIB_DEBUG_PRINT
+/**
+ * Return the number of blocks in the buffer, allocated or unallocated.
+ *
+ * Only available if BUFLIB_DEBUG_PRINT is defined.
+ */
+int buflib_get_num_blocks(struct buflib_context *ctx);
+
+/**
+ * Write a string describing the block at index block_num to the
+ * provided buffer. The buffer will always be null terminated and
+ * there is no provision to detect truncation. (A 40-byte buffer
+ * is enough to contain any returned string.)
+ *
+ * Returns false if the block index is out of bounds, and writes
+ * an empty string.
+ *
+ * Only available if BUFLIB_DEBUG_PRINT is defined.
+ */
+bool buflib_print_block_at(struct buflib_context *ctx, int block_num,
+                           char *buf, size_t bufsize);
+#endif
+
+#ifdef BUFLIB_DEBUG_CHECK_VALID
+/**
+ * Check integrity of given buflib context
+ */
+void buflib_check_valid(struct buflib_context *ctx);
+#endif
 
 #if CONFIG_BUFLIB_BACKEND == BUFLIB_BACKEND_MEMPOOL
 #include "buflib_mempool.h"
 #endif
 
+#ifndef BUFLIB_ALLOC_OVERHEAD
+# define BUFLIB_ALLOC_OVERHEAD 0
+#endif
+
 #endif /* _BUFLIB_H_ */