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// Copyright 2016, VIXL authors
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// * Redistributions of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright notice,
// this list of conditions and the following disclaimer in the documentation
// and/or other materials provided with the distribution.
// * Neither the name of ARM Limited nor the names of its contributors may be
// used to endorse or promote products derived from this software without
// specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS CONTRIBUTORS "AS IS" AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include "examples.h"
#define __ masm->
void GenerateApproximatePi(MacroAssembler* masm) {
// double ApproximatePi(uint32_t iterations)
// Very rough approximation of pi
// pi/4 = 1 - 1/3 + 1/5 - 1/7 + ... + (-1)^n / (2n + 1)
__ Cmp(r0, 0);
__ Bx(eq, lr);
__ Vpush(Untyped64, DRegisterList(d8, d15));
__ Vldr(d0, 1.0);
__ Vldr(d1, 3.0);
__ Vldr(d2, 5.0);
__ Vldr(d3, 7.0);
__ Vmov(d4, 8.0);
__ Vmov(d5, 1.0);
__ Vmov(I64, d10, 0); // d10 = 0.0;
__ Vmov(I64, d11, 0); // d11 = 0.0;
__ Vmov(I64, d12, 0); // d12 = 0.0;
__ Vmov(I64, d13, 0); // d13 = 0.0
Label loop;
__ Bind(&loop);
__ Vdiv(F64, d6, d5, d0);
__ Vdiv(F64, d7, d5, d1);
__ Vdiv(F64, d8, d5, d2);
__ Vdiv(F64, d9, d5, d3);
__ Vadd(F64, d10, d10, d6);
__ Vadd(F64, d11, d11, d7);
__ Vadd(F64, d12, d12, d8);
__ Vadd(F64, d13, d13, d9);
__ Vadd(F64, d0, d0, d4);
__ Vadd(F64, d1, d1, d4);
__ Vadd(F64, d2, d2, d4);
__ Vadd(F64, d3, d3, d4);
__ Subs(r0, r0, 1);
__ B(ne, &loop);
__ Vmov(F64, d4, 4.0);
__ Vadd(F64, d10, d10, d12);
__ Vadd(F64, d11, d11, d13);
__ Vsub(F64, d10, d10, d11);
__ Vmul(F64, d0, d10, d4);
__ Vpop(Untyped64, DRegisterList(d8, d15));
__ Bx(lr);
}
#ifndef TEST_EXAMPLES
int main() {
MacroAssembler masm;
// Generate the code for the example function.
Label pi_approx;
masm.Bind(&pi_approx);
GenerateApproximatePi(&masm);
masm.FinalizeCode();
#ifdef VIXL_INCLUDE_SIMULATOR
// There is no simulator defined for VIXL AArch32.
printf("This example cannot be simulated\n");
#else
byte* code = masm.GetBuffer().GetBuffer();
uint32_t code_size = masm.GetBuffer().GetSizeInBytes();
ExecutableMemory memory(code, code_size);
// Run the example function.
double (*pi_function)(uint32_t) =
memory.GetEntryPoint<double (*)(uint32_t)>(pi_approx);
uint32_t repeat = 10000000;
double output_value = (*pi_function)(repeat);
printf("native: pi_approx(%u) = %3.10f\n", repeat, output_value);
#endif
return 0;
}
#endif // TEST_EXAMPLES
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