diff options
Diffstat (limited to 'magic_buddy/buddy.h')
-rw-r--r-- | magic_buddy/buddy.h | 55 |
1 files changed, 55 insertions, 0 deletions
diff --git a/magic_buddy/buddy.h b/magic_buddy/buddy.h new file mode 100644 index 0000000..c8778d6 --- /dev/null +++ b/magic_buddy/buddy.h @@ -0,0 +1,55 @@ +#pragma once +#include <stdint.h> +#include <stddef.h> + +#define MAGIC_COOKIE_BYTES 32 +#define ADDRESS_BITS (8 * sizeof(void*)) + +struct buddy { + uint8_t magic[MAGIC_COOKIE_BYTES]; + struct free_block *(avail[ADDRESS_BITS]); + size_t root_logsize; + void *base; +}; + +// Initialize a buddy with (constant) global state stored in @state. +// NOTE: after initializing the buddy, you should always pass the exact same +// pointer in for @state in future calls. If you need to move @state, use +// move_buddy(...). +void init_buddy(uint8_t *base, size_t size, uint8_t magic[MAGIC_COOKIE_BYTES], + struct buddy *state); + +// Allocate a block of size >= @size +void *allocate(size_t size, struct buddy *state); + +// Liberate a block of size @size starting at @base. +void liberate(void *base, size_t size, struct buddy *state); + +// Print debug information for the allocator. +void debug_buddy(struct buddy *state); + +// Simulates @new = allocate, memcpy(@new, @old), free(@old), with some +// optimizations for cases where the reallocation can be done in place. +void *reallocate(void *old, size_t old_size, size_t new_size, + struct buddy *state); + +// Attempts to reserve a range [@start,@start+@size). +// Returns 1 if success, 0 otherwise. +// Whenever possible, we avoid writing anything into the reserved region. +int reserve(void *start, size_t size, struct buddy *state); + +// Update @state to assume the memory pool has been copied to +// [@new_base,@new_base+@new_size) +// Can *ONLY* be used when @new_size >= the existing size. +void grow_buddy(uint8_t *new_base, size_t new_size, struct buddy *state); + +// Update @state to only use the subset of the pool in range +// [@state->base,@state->base+new_size) +// Can *ONLY* be used when @new_size <= the existing size. +// This *CAN* write to anything in the old pool. +// This *CAN* fail, in which case everything is unmodified and 0 is returned. +// Upon success, 1 is returned. +int shrink_buddy(size_t new_size, struct buddy *state); + +// Used to move the global state of the buddy. +void move_buddy(struct buddy *new_state, struct buddy *old_state); |