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[/] [or1k/] [tags/] [nog_patch_39/] [or1ksim/] [mmu/] [dmmu.c] - Rev 6
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/* dmmu.c -- data mmu simulation Copyright (C) 1999 Damjan Lampret, lampret@opencores.org This file is part of OpenRISC 1000 Architectural Simulator. This program is free software; you can redistribute it and/or modify it 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., 675 Mass Ave, Cambridge, MA 02139, USA. */ /* DMMU model (not functional yet, currently just copy of data cache). */ #include "dmmu.h" #include "abstract.h" #include "stats.h" /* Data MMU */ unsigned long dmmu_translate(unsigned long virtaddr) { return virtaddr; } /* Number of DC sets (power of 2) */ #define DC_SETS 256 /* Block size in bytes (1, 2, 4, 8, 16, 32 etc.) */ #define DC_BLOCK_SIZE 4 /* Number of DC ways (1, 2, 3 etc.). */ #define DC_WAYS 1 /* Number of usage states (2, 3, 4 etc.). */ #define DC_USTATES 2 struct dc_set { struct { unsigned long tagaddr; /* tag address */ int lru; /* least recently used */ } way[DC_WAYS]; } dc[DC_SETS]; void xdc_info() { printf("Data cache %dKB: ", DC_SETS * DC_BLOCK_SIZE * DC_WAYS / 1024); printf("%d ways, %d sets, block size %d bytes\n", DC_WAYS, DC_SETS, DC_BLOCK_SIZE); } /* First check if data is already in the cache and if it is: - increment DC read hit stats, - set 'lru' at this way to DC_USTATES - 1 and decrement 'lru' of other ways unless they have reached 0, and if not: - increment DC read miss stats - find lru way and entry and replace old tag with tag of the 'dataaddr' - set 'lru' with DC_USTATES - 1 and decrement 'lru' of other ways unless they have reached 0 */ void xdc_simulate_read(unsigned long dataaddr) { int set, way = -1; int i; unsigned long tagaddr; /* Which set to check out? */ set = (dataaddr / DC_BLOCK_SIZE) % DC_SETS; tagaddr = (dataaddr / DC_BLOCK_SIZE) / DC_SETS; /* Scan all ways and try to find a matching way. */ for (i = 0; i < DC_WAYS; i++) if (dc[set].way[i].tagaddr == tagaddr) way = i; /* Did we find our cached data? */ if (way >= 0) { /* Yes, we did. */ dc_stats.readhit++; for (i = 0; i < DC_WAYS; i++) if (dc[set].way[i].lru) dc[set].way[i].lru--; dc[set].way[way].lru = DC_USTATES - 1; } else { /* No, we didn't. */ int minlru = DC_USTATES - 1; int minway = 0; dc_stats.readmiss++; for (i = 0; i < DC_WAYS; i++) if (dc[set].way[i].lru < minlru) minway = i; dc[set].way[minway].tagaddr = tagaddr; for (i = 0; i < DC_WAYS; i++) if (dc[set].way[i].lru) dc[set].way[i].lru--; dc[set].way[minway].lru = DC_USTATES - 1; } } /* First check if data is already in the cache and if it is: - increment DC write hit stats, - set 'lru' at this way to DC_USTATES - 1 and decrement 'lru' of other ways unless they have reached 0, and if not: - increment DC write miss stats - find lru way and entry and replace old tag with tag of the 'dataaddr' - set 'lru' with DC_USTATES - 1 and decrement 'lru' of other ways unless they have reached 0 */ void xdc_simulate_write(unsigned long dataaddr) { int set, way = -1; int i; unsigned long tagaddr; /* Which set to check out? */ set = (dataaddr / DC_BLOCK_SIZE) % DC_SETS; tagaddr = (dataaddr / DC_BLOCK_SIZE) / DC_SETS; /* Scan all ways and try to find a matching way. */ for (i = 0; i < DC_WAYS; i++) if (dc[set].way[i].tagaddr == tagaddr) way = i; /* Did we find our cached data? */ if (way >= 0) { /* Yes, we did. */ dc_stats.writehit++; for (i = 0; i < DC_WAYS; i++) if (dc[set].way[i].lru) dc[set].way[i].lru--; dc[set].way[way].lru = DC_USTATES - 1; } else { /* No, we didn't. */ int minlru = DC_USTATES - 1; int minway = 0; dc_stats.writemiss++; for (i = 0; i < DC_WAYS; i++) if (dc[set].way[i].lru < minlru) minway = i; dc[set].way[minway].tagaddr = tagaddr; for (i = 0; i < DC_WAYS; i++) if (dc[set].way[i].lru) dc[set].way[i].lru--; dc[set].way[minway].lru = DC_USTATES - 1; } }
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