cOMS/utils/BufferMemory.h
2024-07-21 21:25:39 +02:00

125 lines
3.0 KiB
C

/**
* Jingga
*
* @copyright Jingga
* @license OMS License 2.0
* @version 1.0.0
* @link https://jingga.app
*/
#ifndef TOS_UTILS_BUFFER_MEMORY_H
#define TOS_UTILS_BUFFER_MEMORY_H
#include "../stdlib/Types.h"
#include "MathUtils.h"
struct BufferMemory {
byte* memory;
uint64 count;
uint64 element_size;
uint64 last_pos = -1;
// length = count
// free describes which locations are used and which are free
// @performance using uint32 or even uint64 might be faster
// since we can check for free elements faster if the memory is almost filled
// at the moment we can only check 8 elements at a time
byte* free;
};
inline
byte* buffer_element_get(BufferMemory* buf, uint64 element)
{
return buf->memory + element * buf->element_size;
}
int64 buffer_reserve(BufferMemory* buf)
{
int byte_index = (buf->last_pos + 1) / 8;
int bit_index;
int64 free_element = -1;
byte mask;
int i = 0;
int max_loop = buf->count * buf->element_size;
while (free_element < 0 && i < max_loop) {
if (buf->free[byte_index] == 0xFF) {
++i;
++byte_index;
continue;
}
// This always breaks!
// @performance on the first iteration through the buffer we could optimize this by starting at a different bit_index
// because we know that the bit_index is based on last_pos
for (bit_index = 0; bit_index < 8; ++bit_index) {
mask = 1 << bit_index;
if ((buf->free[byte_index] & mask) == 0) {
free_element = byte_index * 8 + bit_index;
break;
}
}
}
if (free_element < 0) {
return -1;
}
buf->free[byte_index] |= (1 << bit_index);
return byte_index * 8 + bit_index;
}
byte* buffer_find_free(BufferMemory* buf, bool zeroed = false)
{
int byte_index = (buf->last_pos + 1) / 8;
int bit_index;
int64 free_element = -1;
byte mask;
int i = 0;
int max_loop = buf->count * buf->element_size;
while (free_element < 0 && i < max_loop) {
if (buf->free[byte_index] == 0xFF) {
++i;
++byte_index;
continue;
}
// This always breaks!
// @performance on the first iteration through the buffer we could optimize this by starting at a different bit_index
// because we know that the bit_index is based on last_pos
for (bit_index = 0; bit_index < 8; ++bit_index) {
mask = 1 << bit_index;
if ((buf->free[byte_index] & mask) == 0) {
free_element = byte_index * 8 + bit_index;
break;
}
}
}
if (free_element < 0) {
return NULL;
}
buf->free[byte_index] |= (1 << bit_index);
return buf->memory + free_element * buf->element_size;
}
inline
void buffer_element_free(BufferMemory* buf, uint64 element)
{
int byte_index = element / 8;
int bit_index = element % 8;
buf->free[byte_index] &= ~(1 << bit_index);
}
#endif