111 lines
3.7 KiB
C++
111 lines
3.7 KiB
C++
// Copyright 2016, VIXL authors
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are met:
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//
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// * Redistributions of source code must retain the above copyright notice,
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// this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above copyright notice,
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// this list of conditions and the following disclaimer in the documentation
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// and/or other materials provided with the distribution.
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// * Neither the name of ARM Limited nor the names of its contributors may be
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// used to endorse or promote products derived from this software without
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// specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS CONTRIBUTORS "AS IS" AND
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// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
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// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#include "examples.h"
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using namespace vixl;
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using namespace vixl::aarch32;
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#define __ masm->
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void GenerateApproximatePi(MacroAssembler* masm) {
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// double ApproximatePi(uint32_t iterations)
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// Very rough approximation of pi
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// pi/4 = 1 - 1/3 + 1/5 - 1/7 + ... + (-1)^n / (2n + 1)
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__ Cmp(r0, 0);
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__ Bx(eq, lr);
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__ Vpush(Untyped64, DRegisterList(d8, 8));
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__ Vldr(d0, 1.0);
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__ Vldr(d1, 3.0);
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__ Vldr(d2, 5.0);
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__ Vldr(d3, 7.0);
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__ Vmov(d4, 8.0);
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__ Vmov(d5, 1.0);
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__ Vmov(I64, d10, 0); // d10 = 0.0;
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__ Vmov(I64, d11, 0); // d11 = 0.0;
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__ Vmov(I64, d12, 0); // d12 = 0.0;
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__ Vmov(I64, d13, 0); // d13 = 0.0
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Label loop;
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__ Bind(&loop);
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__ Vdiv(F64, d6, d5, d0);
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__ Vdiv(F64, d7, d5, d1);
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__ Vdiv(F64, d8, d5, d2);
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__ Vdiv(F64, d9, d5, d3);
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__ Vadd(F64, d10, d10, d6);
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__ Vadd(F64, d11, d11, d7);
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__ Vadd(F64, d12, d12, d8);
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__ Vadd(F64, d13, d13, d9);
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__ Vadd(F64, d0, d0, d4);
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__ Vadd(F64, d1, d1, d4);
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__ Vadd(F64, d2, d2, d4);
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__ Vadd(F64, d3, d3, d4);
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__ Subs(r0, r0, 1);
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__ B(ne, &loop);
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__ Vmov(F64, d4, 4.0);
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__ Vadd(F64, d10, d10, d12);
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__ Vadd(F64, d11, d11, d13);
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__ Vsub(F64, d10, d10, d11);
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__ Vmul(F64, d0, d10, d4);
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__ Vpop(Untyped64, DRegisterList(d8, 8));
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__ Bx(lr);
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}
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#ifndef TEST_EXAMPLES
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int main() {
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MacroAssembler masm;
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// Generate the code for the example function.
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Label pi_approx;
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masm.Bind(&pi_approx);
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GenerateApproximatePi(&masm);
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masm.FinalizeCode();
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#ifdef VIXL_INCLUDE_SIMULATOR_AARCH32
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// There is no simulator defined for VIXL AArch32.
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printf("This example cannot be simulated\n");
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#else
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byte* code = masm.GetBuffer()->GetStartAddress<byte*>();
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uint32_t code_size = masm.GetSizeOfCodeGenerated();
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ExecutableMemory memory(code, code_size);
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// Run the example function.
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double (*pi_function)(uint32_t) =
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memory.GetEntryPoint<double (*)(uint32_t)>(pi_approx,
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masm.GetInstructionSetInUse());
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uint32_t repeat = 10000000;
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double output_value = (*pi_function)(repeat);
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printf("native: pi_approx(%u) = %3.10f\n", repeat, output_value);
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#endif
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return 0;
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}
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#endif // TEST_EXAMPLES
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