fis-gtm/sr_port/bml_find_busy.c

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/****************************************************************
* *
* Copyright 2001, 2007 Fidelity Information Services, Inc *
* *
* This source code contains the intellectual property *
* of its copyright holder(s), and is made available *
* under a license. If you do not know the terms of *
* the license, please stop and do not read further. *
* *
****************************************************************/
#include "mdef.h"
#include "gdsroot.h"
#include "gdsblk.h"
#include "gdsbml.h"
#include "bml_find_busy.h"
#define MAX_FFS_SIZE 32
/* Returns the location of the first clear bit in the field. */
/* The search starts at the hint and wraps if necessary. */
int4 bml_find_busy(int4 hint, uchar_ptr_t base_addr, int4 total_blks)
{
uchar_ptr_t ptr, top;
unsigned char valid;
int4 bits, hint_pos, total_bits, ret_val;
hint_pos = hint * BML_BITS_PER_BLK;
total_bits = total_blks * BML_BITS_PER_BLK;
if (hint_pos >= total_bits)
hint_pos = 0;
hint_pos = hint_pos / 8;
for (ptr = base_addr + hint_pos, top = base_addr + (total_bits + 7) / 8 - 1; ptr < top; ptr++)
{
if ((*ptr & 0x3) == 0)
{
ret_val = (int4)((ptr - base_addr) * (8 / BML_BITS_PER_BLK));
if (ret_val >= hint)
return ret_val;
}
if ((*ptr & 0xc) == 0)
{
ret_val = (int4)((ptr - base_addr) * (8 / BML_BITS_PER_BLK) + 1);
if (ret_val >= hint)
return ret_val;
}
if ((*ptr & 0x30) == 0)
{
ret_val = (int4)((ptr - base_addr) * (8 / BML_BITS_PER_BLK) + 2);
if (ret_val >= hint)
return ret_val;
}
if ((*ptr & 0xc0) == 0)
{
ret_val = (int4)((ptr - base_addr) * (8 / BML_BITS_PER_BLK) + 3);
if (ret_val >= hint)
return ret_val;
}
}
bits = total_bits % 8;
if (bits == 6)
valid = *ptr | 0xc0;
else if (bits == 4)
valid = *ptr | 0xf0;
else if (bits == 2)
valid = *ptr | 0xfc;
else
valid = *ptr;
if ((valid & 0x3) == 0)
{
ret_val = (int4)((ptr - base_addr) * (8 / BML_BITS_PER_BLK));
if (ret_val >= hint)
return ret_val;
}
if ((valid & 0xc) == 0)
{
ret_val = (int4)((ptr - base_addr) * (8 / BML_BITS_PER_BLK) + 1);
if (ret_val >= hint)
return ret_val;
}
if ((valid & 0x30) == 0)
{
ret_val = (int4)((ptr - base_addr) * (8 / BML_BITS_PER_BLK) + 2);
if (ret_val >= hint)
return ret_val;
}
if ((valid & 0xc0) == 0)
{
ret_val = (int4)((ptr - base_addr) * (8 / BML_BITS_PER_BLK) + 3);
if (ret_val >= hint && ret_val <= total_blks)
return ret_val;
}
for (ptr = base_addr, top = base_addr + hint_pos; ptr < top; ptr++)
{
if ((*ptr & 0x3) == 0)
{
return (int4)((ptr - base_addr) * (8 / BML_BITS_PER_BLK));
}
else if ((*ptr & 0xc) == 0)
{
return (int4)((ptr - base_addr) * (8 / BML_BITS_PER_BLK) + 1);
}
else if ((*ptr & 0x30) == 0)
{
return (int4)((ptr - base_addr) * (8 / BML_BITS_PER_BLK) + 2);
}
else if ((*ptr & 0xc0) == 0)
{
return (int4)((ptr - base_addr) * (8 / BML_BITS_PER_BLK) + 3);
}
}
bits = hint % 4;
if (bits == 3)
valid = *ptr | 0xc0;
else if (bits == 2)
valid = *ptr | 0xf0;
else if (bits == 1)
valid = *ptr | 0xfc;
else
valid = *ptr;
if ((valid & 0x3) == 0)
return (int4)((ptr - base_addr) * (8 / BML_BITS_PER_BLK));
if ((valid & 0xc) == 0)
return (int4)((ptr - base_addr) * (8 / BML_BITS_PER_BLK) + 1);
if ((valid & 0x30) == 0)
return (int4)((ptr - base_addr) * (8 / BML_BITS_PER_BLK) + 2);
if ((valid & 0xc0) == 0)
return (int4)((ptr - base_addr) * (8 / BML_BITS_PER_BLK) + 3);
return -1;
}