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vector.c
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vector.c
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/*
* Copyright (c) 2002 Stephen Williams (steve@icarus.com)
*
* This source code is free software; you can redistribute it
* and/or modify it in source code form under the terms of the GNU
* General Public License as published by the Free Software
* Foundation; either version 2 of the License, or (at your option)
* any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#ifdef HAVE_CVS_IDENT
#ident "$Id: vector.c,v 1.5 2005/01/24 05:08:02 steve Exp $"
#endif
# include "vvp_priv.h"
# include <assert.h>
/* Maximum vector bits in a thread. If a thread co-processor is
* implemented, this value may need to be reduced. At that time
* wider operatons will need to be partitioned. For example
* shift operations on WIDE (say > 64k bit) registers.
*/
#define MAX_VEC (256*1024)
static struct allocation_score_s {
ivl_expr_t exp;
unsigned bit;
unsigned alloc : 1;
} allocation_map[MAX_VEC] = { {0} };
/* This is the largest bit to have lookaside values. */
static unsigned lookaside_top = 0;
static inline int peek_bit(unsigned addr)
{
return allocation_map[addr].alloc;
}
static inline void set_bit(unsigned addr)
{
allocation_map[addr].alloc = 1;
}
static inline void clr_bit(unsigned addr)
{
allocation_map[addr].alloc = 0;
}
/*
* This clears a vector that was previously allocated by
* allocate_vector. That is, it unmarks all the bits of the map that
* represent this vector.
*
* If the vector is based in one of 4 constant bit values, then there
* are no bits to clear. If the vector is based in the 4-8 result
* area, then someone is broken.
*/
void clr_vector(struct vector_info vec)
{
unsigned idx;
if (vec.base < 4)
return;
assert(vec.base >= 8);
for (idx = 0 ; idx < vec.wid ; idx += 1)
clr_bit(vec.base + idx);
}
/*
* This unconditionally allocates a stretch of bits from the register
* set. It never returns a bit addressed <8 (0-3 are constant, 4-7 are
* condition codes).
*/
unsigned allocate_vector(unsigned wid)
{
unsigned base = 8;
unsigned idx = 0;
while (idx < wid) {
assert((base + idx) < MAX_VEC);
if (peek_bit(base+idx)) {
base = base + idx + 1;
idx = 0;
} else {
idx += 1;
}
}
for (idx = 0 ; idx < wid ; idx += 1) {
allocation_map[base+idx].alloc = 1;
allocation_map[base+idx].exp = 0;
}
return base;
}
/*
* This clears the expression cache of the allocation map. It is
* called to prevent reuse of existing expressions, normally at the
* start of a basic block.
*/
void clear_expression_lookaside(void)
{
unsigned idx;
for (idx = 0 ; idx < lookaside_top ; idx += 1) {
allocation_map[idx].exp = 0;
}
lookaside_top = 0;
}
void save_expression_lookaside(unsigned addr, ivl_expr_t exp,
unsigned wid)
{
unsigned idx;
assert(addr >= 8);
assert((addr+wid) <= MAX_VEC);
for (idx = 0 ; idx < wid ; idx += 1) {
allocation_map[addr+idx].exp = exp;
allocation_map[addr+idx].bit = idx;
}
if ((addr+wid) > lookaside_top)
lookaside_top = addr+wid;
}
static int compare_exp(ivl_expr_t l, ivl_expr_t r)
{
if (! (l && r))
return 0;
if (l == r)
return 1;
if (ivl_expr_type(l) != ivl_expr_type(r))
return 0;
switch (ivl_expr_type(l)) {
case IVL_EX_SIGNAL:
if (ivl_expr_signal(l) != ivl_expr_signal(r))
return 0;
if (ivl_expr_width(l) != ivl_expr_width(r))
return 0;
return 1;
default:
break;
}
return 0;
}
static unsigned find_expression_lookaside(ivl_expr_t exp,
unsigned wid)
{
unsigned top;
unsigned idx, match;
if (lookaside_top <= wid)
return 0;
top = lookaside_top - wid + 1;
assert(exp);
match = 0;
for (idx = 8 ; idx < top ; idx += 1) {
if (! compare_exp(allocation_map[idx].exp, exp)) {
match = 0;
continue;
}
if (allocation_map[idx].bit != match) {
match = 0;
continue;
}
match += 1;
if (match == wid)
return idx-match+1;
}
return 0;
}
unsigned allocate_vector_exp(ivl_expr_t exp, unsigned wid)
{
unsigned idx;
unsigned la = find_expression_lookaside(exp, wid);
for (idx = 0 ; idx < wid ; idx += 1)
if (allocation_map[la+idx].alloc)
return 0;
for (idx = 0 ; idx < wid ; idx += 1)
allocation_map[la+idx].alloc = 1;
return la;
}
/*
* $Log: vector.c,v $
* Revision 1.5 2005/01/24 05:08:02 steve
* Part selects are done in the compiler, not here.
*
* Revision 1.4 2003/07/03 17:44:10 steve
* Wider thread vector limit.
*
* Revision 1.3 2003/06/17 19:17:42 steve
* Remove short int restrictions from vvp opcodes.
*
* Revision 1.2 2003/06/05 04:18:50 steve
* Better width testing for thread vector allocation.
*
* Revision 1.1 2002/09/27 16:33:34 steve
* Add thread expression lookaside map.
*
*/