project_files/frontlib/buffer.c
author Medo <smaxein@googlemail.com>
Fri, 08 Jun 2012 19:52:24 +0200
changeset 7177 bf6cf4dd847a
parent 7162 fe76d24a25d7
permissions -rw-r--r--
Implemented public API for letting the engine render maps
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#include "buffer.h"
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#include "logging.h"
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#include <stdlib.h>
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#include <limits.h>
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#include <string.h>
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typedef struct _flib_vector {
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	void *data;
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	size_t size;
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	size_t capacity;
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} _flib_vector;
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flib_vector flib_vector_create() {
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	flib_vector result = malloc(sizeof(_flib_vector));
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	if(result == NULL) {
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		return NULL;
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	}
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	result->data = malloc(16);
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	if(result->data == NULL) {
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		free(result);
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		return NULL;
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	}
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	result->size = 0;
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	result->capacity = 16;
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	return result;
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}
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void flib_vector_destroy(flib_vector *vec) {
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	if(vec && *vec) {
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		free((*vec)->data);
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		free(*vec);
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		*vec = NULL;
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	}
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}
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static void try_realloc(flib_vector vec, size_t newCapacity) {
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	void *newData = realloc(vec->data, newCapacity);
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	if(newData) {
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		vec->data = newData;
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		vec->capacity = newCapacity;
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	}
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}
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static size_t getFreeCapacity(flib_vector vec) {
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	return vec->capacity - vec->size;
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}
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int flib_vector_append(flib_vector vec, const void *data, size_t len) {
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	if(getFreeCapacity(vec) < len) {
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		// Resize exponentially for constant amortized time,
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		// But at least by as much as we need of course,
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		// and be extra careful with integer overflows...
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		size_t extraCapacity = (vec->capacity)/2;
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		size_t minExtraCapacity = len - getFreeCapacity(vec);
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		if(extraCapacity < minExtraCapacity) {
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			extraCapacity = minExtraCapacity;
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		}
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		if(extraCapacity <= SIZE_MAX - vec->capacity) {
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			try_realloc(vec, vec->capacity+extraCapacity);
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		}
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		// Check if we were able to resize.
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		// If not, try to allocate at least what we need...
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		if(getFreeCapacity(vec) < len) {
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			try_realloc(vec, vec->capacity+minExtraCapacity);
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			// Still not working? Then we fail.
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			if(getFreeCapacity(vec) < len) {
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				return 0;
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			}
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		}
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	}
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	memmove(vec->data + vec->size, data, len);
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	vec->size += len;
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	return len;
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}
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flib_buffer flib_vector_as_buffer(flib_vector vec) {
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	flib_buffer result = {vec->data, vec->size};
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	return result;
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}
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flib_constbuffer flib_vector_as_constbuffer(flib_vector vec) {
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	flib_constbuffer result = {vec->data, vec->size};
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	return result;
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}