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Diffstat (limited to 'firmware/include/buflib.h')
| -rw-r--r-- | firmware/include/buflib.h | 359 |
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_ */ |