1 // Copyright 2015, VIXL authors
2 // All rights reserved.
3 //
4 // Redistribution and use in source and binary forms, with or without
5 // modification, are permitted provided that the following conditions are met:
6 //
7 // * Redistributions of source code must retain the above copyright notice,
8 // this list of conditions and the following disclaimer.
9 // * Redistributions in binary form must reproduce the above copyright notice,
10 // this list of conditions and the following disclaimer in the documentation
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12 // * Neither the name of ARM Limited nor the names of its contributors may be
13 // used to endorse or promote products derived from this software without
14 // specific prior written permission.
15 //
16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS CONTRIBUTORS "AS IS" AND
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25 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26
27 #include "examples.h"
28
29 // Macro to compute the number of elements in a vector.
30 #define ARRAY_SIZE(Array) (sizeof(Array) / sizeof((Array)[0]))
31 #define __ masm->
32
33 /*
34 * This example adds two vectors with 1-byte elements using NEON instructions,
35 * and returns the results in the first vector.
36 */
GenerateAdd2Vectors(MacroAssembler * masm)37 void GenerateAdd2Vectors(MacroAssembler* masm) {
38 // void add2_vectors(uint8_t *vec*, const uint8_t *vecB, unsigned size)
39 // Argument locations:
40 // vecA (pointer) -> x0
41 // vecB (pointer) -> x1
42 // size (integer) -> w2
43 // Result returned in vecA.
44
45 Label loop16, loopr, end;
46
47 // Loop to add vector elements in 16-byte chunks.
48 __ Bind(&loop16);
49
50 // Handle vectors smaller than 16-bytes in the remainder loop.
51 __ Cmp(w2, 16);
52 __ B(lo, &loopr);
53 __ Sub(w2, w2, 16);
54
55 // Add vectors in 16-byte chunks.
56 __ Ld1(v0.V16B(), MemOperand(x0));
57 __ Ld1(v1.V16B(), MemOperand(x1, 16, PostIndex));
58 __ Add(v0.V16B(), v0.V16B(), v1.V16B());
59 __ St1(v0.V16B(), MemOperand(x0, 16, PostIndex));
60
61 __ B(&loop16);
62
63 // Loop to add the remaining vector elements.
64 __ Bind(&loopr);
65
66 // If there are no more vector elements to process, then exit.
67 __ Cbz(w2, &end);
68 __ Sub(w2, w2, 1);
69
70 // Add remaining vector elements in 1-byte chunks.
71 __ Ldrb(w5, MemOperand(x0));
72 __ Ldrb(w6, MemOperand(x1, 1, PostIndex));
73 __ Add(w5, w5, w6);
74 __ Strb(w5, MemOperand(x0, 1, PostIndex));
75
76 __ B(&loopr);
77
78 __ Bind(&end);
79
80 __ Ret();
81 }
82
83
PrintVector(const uint8_t * vec,unsigned num)84 void PrintVector(const uint8_t* vec, unsigned num) {
85 unsigned i;
86 printf("( ");
87 if (num > 0) {
88 for (i = 0; i < num - 1; ++i) {
89 printf("%d, ", vec[i]);
90 }
91 printf("%d", vec[i]);
92 }
93 printf(" )\n");
94 }
95
96
97 #ifndef TEST_EXAMPLES
main(void)98 int main(void) {
99 MacroAssembler masm;
100
101 // Generate native code for the example function.
102 Label add2_vectors;
103 masm.Bind(&add2_vectors);
104 GenerateAdd2Vectors(&masm);
105 masm.FinalizeCode();
106
107 // Initialize input data for the example function.
108 // clang-format: off
109 uint8_t vecA[] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,
110 13, 14, 15, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
111 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20};
112 uint8_t vecB[] = {16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28,
113 29, 30, 31, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,
114 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36};
115 // clang-format on
116 uint8_t vecC[ARRAY_SIZE(vecA)];
117
118 // Check whether the number of elements in both vectors match.
119 VIXL_CHECK(ARRAY_SIZE(vecA) == ARRAY_SIZE(vecB));
120
121 // Compute the result in C.
122 for (unsigned i = 0; i < ARRAY_SIZE(vecA); i++) {
123 vecC[i] = vecA[i] + vecB[i];
124 }
125
126 #ifdef VIXL_INCLUDE_SIMULATOR_AARCH64
127 uintptr_t vecA_addr = reinterpret_cast<uintptr_t>(vecA);
128 uintptr_t vecB_addr = reinterpret_cast<uintptr_t>(vecB);
129
130 // Configure register environment in the simulator.
131 Decoder decoder;
132 Simulator simulator(&decoder);
133 simulator.WriteXRegister(0, vecA_addr);
134 simulator.WriteXRegister(1, vecB_addr);
135 simulator.WriteXRegister(2, ARRAY_SIZE(vecA));
136 PrintVector(vecA, ARRAY_SIZE(vecA));
137 printf(" +\n");
138 PrintVector(vecB, ARRAY_SIZE(vecB));
139
140 // Run the example function in the simulator.
141 simulator.RunFrom(masm.GetLabelAddress<Instruction*>(&add2_vectors));
142 printf(" =\n");
143 PrintVector(vecA, ARRAY_SIZE(vecA));
144
145 // Check that the computed value in NEON matches the C version.
146 for (unsigned i = 0; i < ARRAY_SIZE(vecA); i++) {
147 VIXL_CHECK(vecC[i] == vecA[i]);
148 }
149 #else
150 USE(vecC);
151
152 // Placeholder to run test natively.
153 printf("Running tests natively is not supported yet.\n");
154 #endif // VIXL_INCLUDE_SIMULATOR_AARCH64
155
156 return 0;
157 }
158 #endif // TEST_EXAMPLES
159