Files
wren/include/wren.h
2013-12-20 07:41:35 -08:00

84 lines
3.1 KiB
C

#ifndef wren_h
#define wren_h
#include <stdlib.h>
typedef struct WrenVM WrenVM;
// A generic allocation function that handles all explicit memory management
// used by Wren. It's used like so:
//
// - To allocate new memory, [memory] is NULL and [oldSize] is zero. It should
// return the allocated memory or NULL on failure.
//
// - To attempt to grow an existing allocation, [memory] is the memory,
// [oldSize] is its previous size, and [newSize] is the desired size.
// It should return [memory] if it was able to grow it in place, or a new
// pointer if it had to move it.
//
// - To shrink memory, [memory], [oldSize], and [newSize] are the same as above
// but it will always return [memory].
//
// - To free memory, [memory] will be the memory to free and [newSize] and
// [oldSize] will be zero. It should return NULL.
typedef void* (*WrenReallocateFn)(void* memory, size_t oldSize, size_t newSize);
typedef struct
{
// The callback Wren will use to allocate, reallocate, and deallocate memory.
//
// If `NULL`, defaults to a built-in function that uses `realloc` and `free`.
WrenReallocateFn reallocateFn;
// The number of bytes Wren will allocate before triggering the first garbage
// collection.
//
// If zero, defaults to 10MB.
size_t initialHeapSize;
// After a collection occurs, the threshold for the next collection is
// determined based on the number of bytes remaining in use. This allows Wren
// to shrink its memory usage automatically after reclaiming a large amount
// of memory.
//
// This can be used to ensure that the heap does not get too small, which can
// in turn lead to a large number of collections afterwards as the heap grows
// back to a usable size.
//
// If zero, defaults to 1MB.
size_t minHeapSize;
// Wren will grow (and shrink) the heap automatically as the number of bytes
// remaining in use after a collection changes. This number determines the
// amount of additional memory Wren will use after a collection, as a
// percentage of the current heap size.
//
// For example, say that this is 50. After a garbage collection, Wren there
// are 400 bytes of memory still in use. That means the next collection will
// be triggered after a total of 600 bytes are allocated (including the 400
// already in use.
//
// Setting this to a smaller number wastes less memory, but triggers more
// frequent garbage collections.
//
// If zero, defaults to 50.
int heapGrowthPercent;
} WrenConfiguration;
// Creates a new Wren virtual machine using the given [configuration]. Wren
// will copy the configuration data, so the argument passed to this can be
// freed after calling this. If [configuration] is `NULL`, uses a default
// configuration.
WrenVM* wrenNewVM(WrenConfiguration* configuration);
// Disposes of all resources is use by [vm], which was previously created by a
// call to [wrenNewVM].
void wrenFreeVM(WrenVM* vm);
// Runs [source], a string of Wren source code in a new fiber in [vm]. Returns
// zero if successful.
// TODO: Define error codes.
int wrenInterpret(WrenVM* vm, const char* source);
#endif