1 /******************************************************************************
2 * Filename: cpu.c
3 *
4 * Description: Instruction wrappers for special CPU instructions needed by
5 * the drivers.
6 *
7 * Copyright (c) 2022-2023 Texas Instruments Incorporated
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions are met:
11 *
12 * 1) Redistributions of source code must retain the above copyright notice,
13 * this list of conditions and the following disclaimer.
14 *
15 * 2) Redistributions in binary form must reproduce the above copyright notice,
16 * this list of conditions and the following disclaimer in the documentation
17 * and/or other materials provided with the distribution.
18 *
19 * 3) Neither the name of the copyright holder nor the names of its
20 * contributors may be used to endorse or promote products derived from this
21 * software without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
24 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
27 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
28 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
29 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
30 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
31 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
32 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
33 * POSSIBILITY OF SUCH DAMAGE.
34 *
35 ******************************************************************************/
36
37 #include "cpu.h"
38
39 //*****************************************************************************
40 //
41 // Provide a small delay
42 //
43 //*****************************************************************************
44 #if defined(DOXYGEN)
CPUDelay(uint32_t count)45 void CPUDelay(uint32_t count)
46 {
47 // This function is written in assembly. See cpu.c for compiler specific implementation.
48 }
49 #elif defined(__IAR_SYSTEMS_ICC__)
CPUDelay(uint32_t count)50 void CPUDelay(uint32_t count)
51 {
52 // Loop the specified number of times
53 __asm("CPUDelay:\n"
54 " subs r0, #1\n"
55 " bne.n CPUDelay\n"
56 " bx lr");
57 #pragma diag_suppress = Pe940
58 }
59 #pragma diag_default = Pe940
60 #elif defined(__clang__)
CPUDelay(uint32_t count)61 void __attribute__((naked)) CPUDelay(uint32_t count)
62 {
63 // Loop the specified number of times.
64 // The naked attribute tells the compiler that the function is effectively
65 // hand-coded assembly implemented using inlined assembly without operands.
66 // As such, it assumes that the C calling conventions are obeyed, and we can
67 // assume count is in R0.
68 __asm volatile("CPUdel%=:\n"
69 " subs r0, #1\n"
70 " bne CPUdel%=\n"
71 " bx lr\n"
72 : /* No output */
73 : /* No input */
74 : "r0", "cc" /* Clobbers. "cc" is the flags */
75 );
76 }
77 #elif defined(__GNUC__)
CPUDelay(uint32_t count)78 void __attribute__((naked)) CPUDelay(uint32_t count)
79 {
80 // Loop the specified number of times
81 __asm volatile(".syntax unified\n"
82 "CPUdel%=:\n"
83 " subs %0, #1\n"
84 " bne CPUdel%=\n"
85 " bx lr\n"
86 : /* No output */
87 : "r"(count) /* Input */
88 );
89 }
90 #else
91 #error "Unsupported toolchain!"
92 #endif
93
