cosmopolitan/libc/str/getcachesize.c

59 lines
2.8 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ 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; version 2 of the License. │
│ │
│ 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., 51 Franklin Street, Fifth Floor, Boston, MA │
│ 02110-1301 USA │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/assert.h"
#include "libc/bits/bits.h"
#include "libc/dce.h"
#include "libc/nexgen32e/cachesize.h"
#include "libc/nexgen32e/cpuid4.h"
static unsigned getcachesize$cpuid4(int type, int level) {
unsigned i, k;
static int once;
static unsigned char kCacheKey[8];
static unsigned kCacheSize[8];
if (!once) {
CPUID4_ITERATE(i, {
kCacheKey[i] = CPUID4_KEY;
kCacheSize[i] = CPUID4_CACHE_SIZE_IN_BYTES;
});
once = 1;
}
k = ((level & 7) << 5) | (type & 31);
for (i = 0; i < 8; ++i) {
if (kCacheKey[i] == k) {
return kCacheSize[i];
}
}
return 0;
}
/**
* Returns CPU cache size.
*
* @param type 1=data, 2=instruction, 3=unified
* @param level starts at 1
* @return size in bytes, or 0 if unknown
*/
unsigned getcachesize(enum CpuCacheType type, int level) {
assert(1 <= type && type <= 3);
assert(level >= 1);
return getcachesize$cpuid4(type, level);
}