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/*
* COPYRIGHT (c) 2019 Chris Johns <chrisj@rtems.org>
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.org/license/LICENSE.
*/
/**
* @file
*
* @ingroup rtems_rtld
*
* @brief RTEMS Run-Time Link Editor Bit Allocator
*
* A configurable allocator for small peices of memory where embedding
* control blocks into the memory are not viable. The amount of memory
* should be small and the minimum allocator a 32bit work or higher.
*/
#if HAVE_CONFIG_H
#include "config.h"
#endif
#include <errno.h>
#include <inttypes.h>
#include <stdio.h>
#include <string.h>
#include <rtems/rtl/rtl-allocator.h>
#include "rtl-bit-alloc.h"
#include "rtl-error.h"
#include <rtems/rtl/rtl-trace.h>
#define BITS_PER_WORD (sizeof (uint32_t) * 8)
static size_t
bit_blocks (rtems_rtl_bit_alloc* balloc, size_t size)
{
if (size == 0)
return 0;
return ((size - 1) / balloc->block_size) + 1;
}
static size_t
bit_word (size_t bit)
{
return bit / BITS_PER_WORD;
}
static size_t
bit_offset (size_t bit)
{
return bit % (sizeof (uint32_t) * 8);
}
static uint32_t
bit_mask (size_t bit)
{
return 1 << bit_offset (bit);
}
static void
bit_set (rtems_rtl_bit_alloc* balloc, size_t start, size_t bits)
{
size_t b;
for (b = start; b < (start + bits); ++b)
balloc->bits[bit_word (b)] |= bit_mask (b);
}
static void
bit_clear (rtems_rtl_bit_alloc* balloc, size_t start, size_t bits)
{
size_t b;
for (b = start; b < (start + bits); ++b)
balloc->bits[bit_word (b)] &= ~bit_mask (b);
}
static ssize_t
bit_find_clear (rtems_rtl_bit_alloc* balloc, size_t blocks)
{
size_t base = 0;
size_t clear = 0;
size_t b;
for (b = 0; b < balloc->blocks; ++b)
{
if (balloc->bits[b] != 0xffffffff)
{
uint32_t word = balloc->bits[b];
size_t o;
for (o = 0; o < BITS_PER_WORD; ++o, word >>= 1)
{
if ((word & 1) == 0)
{
if (clear == 0)
base = (b * BITS_PER_WORD) + o;
++clear;
if (clear == blocks)
return base;
}
else
{
clear = 0;
base = 0;
}
}
}
else
{
clear = 0;
base = 0;
}
}
return -1;
}
rtems_rtl_bit_alloc*
rtems_rtl_bit_alloc_open (void* base, size_t size, size_t block_size, size_t used)
{
rtems_rtl_bit_alloc* balloc;
const size_t base_size = base == NULL ? size : 0;;
const size_t blocks = (size / block_size) / BITS_PER_WORD;
const size_t bit_bytes = blocks * sizeof(uint32_t);
if (rtems_rtl_trace (RTEMS_RTL_TRACE_BIT_ALLOC))
printf ("rtl: balloc: open: base=%p size=%zu" \
" block-size=%zu blocks=%zu used=%zu\n",
base, size, block_size, blocks, used);
if (size == 0)
{
rtems_rtl_set_error (ENOMEM, "bit allocator size is 0");
return false;
}
if (used > size)
{
rtems_rtl_set_error (ENOMEM, "bad bit allocator used value");
return false;
}
balloc = rtems_rtl_alloc_new (RTEMS_RTL_ALLOC_OBJECT,
sizeof (rtems_rtl_bit_alloc) + bit_bytes + base_size,
true);
if (balloc == NULL)
{
rtems_rtl_set_error (ENOMEM, "not bit allocator memory");
return NULL;
}
balloc->base =
base == NULL ? ((void*) balloc) + sizeof (rtems_rtl_bit_alloc) + bit_bytes: base;
balloc->size = size;
balloc->bits = ((void*) balloc) + sizeof (rtems_rtl_bit_alloc);
balloc->block_size = block_size;
balloc->blocks = blocks;
bit_set (balloc, 0, bit_blocks (balloc, used));
return balloc;
}
void
rtems_rtl_bit_alloc_close (rtems_rtl_bit_alloc* balloc)
{
if (rtems_rtl_trace (RTEMS_RTL_TRACE_BIT_ALLOC))
printf ("rtl: balloc: close: base=%p size=%zu\n",
balloc->base, balloc->size);
rtems_rtl_alloc_del (RTEMS_RTL_ALLOC_OBJECT, balloc);
}
void*
rtems_rtl_bit_alloc_balloc (rtems_rtl_bit_alloc* balloc, size_t size)
{
size_t blocks = bit_blocks (balloc, size);
ssize_t block = bit_find_clear (balloc, blocks);
if (block < 0)
return NULL;
if (rtems_rtl_trace (RTEMS_RTL_TRACE_BIT_ALLOC))
printf ("rtl: balloc: balloc: size=%zu blocks=%zu block=%zi\n",
size, blocks, block);
bit_set (balloc, block, blocks);
return (void*) (balloc->base + (block * balloc->block_size));
}
void
rtems_rtl_bit_alloc_bfree (rtems_rtl_bit_alloc* balloc, void* addr, size_t size)
{
const uint8_t* a = (const uint8_t*) addr;
if (addr != NULL && a >= balloc->base && a < balloc->base + balloc->size)
{
size_t block = bit_blocks (balloc, a - balloc->base);
size_t blocks = bit_blocks (balloc, size);
bit_clear (balloc, block, blocks);
}
}
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