1 /*
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright © 2019 Keith Packard
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 *
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 *
13 * 2. Redistributions in binary form must reproduce the above
14 * copyright notice, this list of conditions and the following
15 * disclaimer in the documentation and/or other materials provided
16 * with the distribution.
17 *
18 * 3. Neither the name of the copyright holder nor the names of its
19 * contributors may be used to endorse or promote products derived
20 * from this software without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
23 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
24 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
25 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
26 * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
27 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
28 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
29 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
31 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
32 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
33 * OF THE POSSIBILITY OF SUCH DAMAGE.
34 */
35
36 #include "../../crt0.h"
37
38 static void __attribute__((used)) __section(".text.startup")
_cstart(void)39 _cstart(void)
40 {
41 __start();
42 }
43
44 extern char __stack[];
45
46 #define FPSCR_FR (1 << 21)
47 #define FPSCR_SZ (1 << 20)
48 #define FPSCR_PR (1 << 19)
49 #define FPSCR_DN (1 << 18)
50 #define FPSCR_RN (0 << 0)
51 #define FPSCR_RM (3 << 0)
52
53 void __section(".init") __attribute__((used))
_start(void)54 _start(void)
55 {
56 /* Set up the stack pointer */
57 __asm__("mov %0, r15" : : "r" (__stack));
58
59 /* Initialize the FPU */
60 #ifdef __SH_FPU_ANY__
61 long fpscr;
62 __asm__("sts fpscr,%0" : "=r" (fpscr));
63 /* enable denorms */
64 fpscr &= ~FPSCR_DN;
65 /* set round to nearest */
66 fpscr &= ~FPSCR_RM;
67 fpscr |= FPSCR_RN;
68 #ifdef __SH4__
69 fpscr |= FPSCR_PR;
70 #elif defined(__SH4_SINGLE_ONLY__)
71 fpscr &= ~FPSCR_PR;
72 #endif
73 __asm__("lds %0,fpscr" : : "r" (fpscr));
74 #endif
75 /* Branch to C code */
76 __asm__("jmp @%0" : : "r" (_cstart));
77
78 /* Fill in any delay slot */
79 __asm__("nop");
80 }
81
