1 // Copyright 2014, 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
11 // and/or other materials provided with the distribution.
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
17 // ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
18 // WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
19 // DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
20 // FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 // DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
22 // SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
23 // CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 // OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
25 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26
27 #include "examples.h"
28
29 #define __ masm->
30
GenerateCheckBounds(MacroAssembler * masm)31 void GenerateCheckBounds(MacroAssembler* masm) {
32 // uint64_t check_bounds(uint64_t value, uint64_t low, uint64_t high)
33 // Argument locations:
34 // value -> x0
35 // low -> x1
36 // high -> x2
37
38 // First we compare 'value' with the 'low' bound. If x1 <= x0 the N flag will
39 // be cleared. This configuration can be checked with the 'pl' condition.
40 __ Cmp(x0, x1);
41
42 // Now we will compare 'value' and 'high' (x0 and x2) but only if the 'pl'
43 // condition is verified. If the condition is not verified, we will clear
44 // all the flags except the carry one (C flag).
45 __ Ccmp(x0, x2, CFlag, pl);
46
47 // We set x0 to 1 only if the 'ls' condition is satisfied.
48 // 'ls' performs the following test: !(C==1 && Z==0). If the previous
49 // comparison has been skipped we have C==1 and Z==0, so the 'ls' test
50 // will fail and x0 will be set to 0.
51 // Otherwise if the previous comparison occurred, x0 will be set to 1
52 // only if x0 is less than or equal to x2.
53 __ Cset(x0, ls);
54
55 __ Ret();
56 }
57
58
59 #ifndef TEST_EXAMPLES
60 #ifdef VIXL_INCLUDE_SIMULATOR_AARCH64
run_function(Simulator * simulator,Instruction * function,uint64_t value,uint64_t low,uint64_t high)61 void run_function(Simulator* simulator,
62 Instruction* function,
63 uint64_t value,
64 uint64_t low,
65 uint64_t high) {
66 simulator->WriteXRegister(0, value);
67 simulator->WriteXRegister(1, low);
68 simulator->WriteXRegister(2, high);
69
70 simulator->RunFrom(function);
71 printf("%" PRIu64 " %s between %" PRIu64 " and %" PRIu64 "\n",
72 value,
73 simulator->ReadXRegister(0) ? "is" : "is not",
74 low,
75 high);
76
77 simulator->ResetState();
78 }
79
main(void)80 int main(void) {
81 MacroAssembler masm;
82 Decoder decoder;
83 Simulator simulator(&decoder);
84
85 // Generate the code for the example function.
86 Label check_bounds;
87 masm.Bind(&check_bounds);
88 GenerateCheckBounds(&masm);
89 masm.FinalizeCode();
90
91 // Run the example function.
92 Instruction* function = masm.GetLabelAddress<Instruction*>(&check_bounds);
93 run_function(&simulator, function, 546, 50, 1000);
94 run_function(&simulator, function, 62, 100, 200);
95 run_function(&simulator, function, 200, 100, 200);
96
97 return 0;
98 }
99 #else
100 // Without the simulator there is nothing to test.
main(void)101 int main(void) { return 0; }
102 #endif // VIXL_INCLUDE_SIMULATOR_AARCH64
103 #endif // TEST_EXAMPLES
104