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 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 31 void GenerateCrc32(MacroAssembler* masm) { 32 // uint32_t crc32(const char *msg, size_t length) 33 // Argument location: 34 // msg (pointer) -> x0 35 // length (integer) -> x1 36 37 // This example computes CRC32CB on an input array of a given size 38 // and returns the resulting checksum in w0. 39 40 Label loop, end; 41 42 // Move input array to temp register so we can re-use w0 as return register. 43 __ Mov(x2, x0); 44 45 // Initial remainder for the checksum. If length=0, then this value will be 46 // returned. 47 __ Mov(w0, 0xffffffff); 48 49 // Loop for iterating through the array, starting at msg[0]. 50 __ Bind(&loop); 51 52 // If no more elements to process, then exit function. 53 __ Cbz(x1, &end); 54 __ Sub(x1, x1, 1); 55 56 // Compute checksum for msg[i]. 57 __ Ldrb(w3, MemOperand(x2, 1, PostIndex)); 58 __ Crc32b(w0, w0, w3); 59 __ B(&loop); 60 61 __ Bind(&end); 62 63 __ Ret(); 64 } 65 66 #ifndef TEST_EXAMPLES 67 68 void runExample(const char* msg) { 69 MacroAssembler masm; 70 71 // Generate the code for the example function. 72 Label func; 73 masm.Bind(&func); 74 GenerateCrc32(&masm); 75 masm.FinalizeCode(); 76 77 #ifdef VIXL_INCLUDE_SIMULATOR_AARCH64 78 // Run example function in the simulator. 79 uintptr_t msg_addr = reinterpret_cast<uintptr_t>(msg); 80 size_t msg_size = strlen(msg); 81 Decoder decoder; 82 Simulator simulator(&decoder); 83 simulator.WriteXRegister(0, msg_addr); 84 simulator.WriteXRegister(1, msg_size); 85 simulator.RunFrom(masm.GetLabelAddress<Instruction*>(&func)); 86 printf("crc32(\"%s\")=0x%x\n", msg, simulator.ReadWRegister(0)); 87 #else 88 // Run example function natively. 89 printf("Not yet implemented.\n"); 90 USE(msg); 91 #endif // VIXL_INCLUDE_SIMULATOR_AARCH64 92 } 93 94 95 int main(void) { 96 runExample("Hello World!"); 97 runExample("do"); 98 runExample("1"); 99 runExample(""); 100 101 return 0; 102 } 103 #endif // TEST_EXAMPLES 104
