1 /*****************************************************************************
2 * cpu-a.S: arm cpu detection
3 *****************************************************************************
4 * Copyright (C) 2009-2011 x264 project
6 * Authors: David Conrad <lessen42@gmail.com>
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02111, USA.
22 * This program is also available under a commercial proprietary license.
23 * For more information, contact us at licensing@x264.com.
24 *****************************************************************************/
31 // done in gas because .fpu neon overrides the refusal to assemble
32 // instructions the selected -march/-mcpu doesn't support
33 function x264_cpu_neon_test
38 // return: 0 on success
39 // 1 if counters were already enabled
40 // 9 if lo-res counters were already enabled
41 function x264_cpu_enable_armv7_counter
42 mrc p15, 0, r2, c9, c12, 0 // read PMNC
46 orr r2, r2, #1 // enable counters
47 bic r2, r2, #8 // full resolution
48 mcreq p15, 0, r2, c9, c12, 0 // write PMNC
49 mov r2, #1 << 31 // enable cycle counter
50 mcr p15, 0, r2, c9, c12, 1 // write CNTENS
54 function x264_cpu_disable_armv7_counter
55 mrc p15, 0, r0, c9, c12, 0 // read PMNC
56 bic r0, r0, #1 // disable counters
57 mcr p15, 0, r0, c9, c12, 0 // write PMNC
63 mrc p15, 0, \r, c9, c13, 0
66 // return: 0 if transfers neon -> arm transfers take more than 10 cycles
68 function x264_cpu_fast_neon_mrc_test
69 // check for user access to performance counters
70 mrc p15, 0, r0, c9, c14, 0
75 bl x264_cpu_enable_armv7_counter
96 cmpgt r2, #30 << 3 // assume context switch if it took over 30 cycles
101 // disable counters if we enabled them
103 bleq x264_cpu_disable_armv7_counter