1 /*
2 * MIPS SIMD Architecture Module Instruction emulation helpers for QEMU.
3 *
4 * Copyright (c) 2014 Imagination Technologies
5 *
6 * This library is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
10 *
11 * This library is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with this library; if not, see <http://www.gnu.org/licenses/>.
18 */
19
20 #include "qemu/osdep.h"
21 #include "cpu.h"
22 #include "internal.h"
23 #include "fpu/softfloat.h"
24 #include "fpu_helper.h"
25
msa_reset(CPUMIPSState * env)26 void msa_reset(CPUMIPSState *env)
27 {
28 if (!ase_msa_available(env)) {
29 return;
30 }
31
32 #ifdef CONFIG_USER_ONLY
33 /* MSA access enabled */
34 env->CP0_Config5 |= 1 << CP0C5_MSAEn;
35 env->CP0_Status |= (1 << CP0St_CU1) | (1 << CP0St_FR);
36 #endif
37
38 /*
39 * MSA CSR:
40 * - non-signaling floating point exception mode off (NX bit is 0)
41 * - Cause, Enables, and Flags are all 0
42 * - round to nearest / ties to even (RM bits are 0)
43 */
44 env->active_tc.msacsr = 0;
45
46 restore_msa_fp_status(env);
47
48 /* tininess detected after rounding.*/
49 set_float_detect_tininess(float_tininess_after_rounding,
50 &env->active_tc.msa_fp_status);
51
52 /*
53 * According to MIPS specifications, if one of the two operands is
54 * a sNaN, a new qNaN has to be generated. This is done in
55 * floatXX_silence_nan(). For qNaN inputs the specifications
56 * says: "When possible, this QNaN result is one of the operand QNaN
57 * values." In practice it seems that most implementations choose
58 * the first operand if both operands are qNaN. In short this gives
59 * the following rules:
60 * 1. A if it is signaling
61 * 2. B if it is signaling
62 * 3. A (quiet)
63 * 4. B (quiet)
64 * A signaling NaN is always silenced before returning it.
65 */
66 set_float_2nan_prop_rule(float_2nan_prop_s_ab,
67 &env->active_tc.msa_fp_status);
68
69 /* clear float_status exception flags */
70 set_float_exception_flags(0, &env->active_tc.msa_fp_status);
71
72 /* clear float_status nan mode */
73 set_default_nan_mode(0, &env->active_tc.msa_fp_status);
74
75 /* set proper signanling bit meaning ("1" means "quiet") */
76 set_snan_bit_is_one(0, &env->active_tc.msa_fp_status);
77 }
78