examples/aarch32/mandelbrot.cc - platform/external/vixl - Git at Google

 // Copyright 2017, 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 GenerateMandelBrot(MacroAssembler* masm) {
   const QRegister kCReal = q0;
   const QRegister kCImag = q1;

   const QRegister kCRealStep = q13;
   const QRegister kCImagStep = q14;

   const QRegister kModSqLimit = q15;

   // Save register values.
   __ Push(RegisterList(r4, r5, r6));

   __ Vmov(F32, kCRealStep, 0.125);
   __ Vmov(F32, kCImagStep, 0.0625);

   const Register kZero = r2;
   __ Mov(kZero, 0);

   const DRegister kStars = d6;
   const DRegister kSpaces = d7;
   // Output characters - packed 4 characters into 32 bits.
   __ Vmov(I8, kStars, '*');
   __ Vmov(I8, kSpaces, ' ');

   const DRegisterLane kNegTwo = DRegisterLane(d7, 1);
   __ Vmov(s15, -2.0);

   // Imaginary part of c.
   __ Vdup(Untyped32, kCImag, kNegTwo);

   // Max modulus squared.
   __ Vmov(F32, kModSqLimit, 4.0);

   // Height of output in characters.
   __ Mov(r4, 64);

   // String length will be 129, so need 132 bytes of space.
   const uint32_t kStringLength = 132;

   // Make space for our string.
   __ Sub(sp, sp, kStringLength);

   // Set up a starting pointer for the string.
   const Register kStringPtr = r6;
   __ Mov(kStringPtr, sp);

   // Loop over imaginary values of c from -2 to 2, taking
   // 64 equally spaced values in the range.
   {
     Label c_imag_loop;

     __ Bind(&c_imag_loop);

     // Real part of c.
     // Store 4 equally spaced values in q0 (kCReal) to use SIMD.
     __ Vmov(s0, -2.0);
     __ Vmov(s1, -1.96875);
     __ Vmov(s2, -1.9375);
     __ Vmov(s3, -1.90625);

     // Width of output in terms of sets of 4 characters - twice that
     // of height to compensate for ratio of character height to width.
     __ Mov(r5, 32);

     const Register kWriteCursor = r3;
     // Set a cursor ready to write the next line.
     __ Mov(kWriteCursor, kStringPtr);

     // Loop over real values of c from -2 to 2, processing
     // 4 different values simultaneously using SIMD.
     {
       const QRegister kFlags = q2;
       const DRegister kLowerFlags = d4;

       Label c_real_loop;
       __ Bind(&c_real_loop);

       // Get number of iterations.
       __ Add(r1, r0, 1);

       // Perform the iterations of z(n+1) = zn^2 + c using SIMD.
       // If the result is that c is in the set, the element of
       // kFlags will be 0, else ~0.
       {
         const QRegister kZReal = q8;
         const QRegister kZImag = q9;

         // Real part of z.
         __ Vmov(F32, kZReal, 0.0);

         // Imaginary part of z.
         __ Vmov(F32, kZImag, 0.0);

         __ Vmov(F32, kFlags, 0.0);

         Label iterative_formula_start, iterative_formula_end;
         __ Bind(&iterative_formula_start);
         __ Subs(r1, r1, 1);
         __ B(le, &iterative_formula_end);

         // z(n+1) = zn^2 + c.
         // re(z(n+1)) = re(c) + re(zn)^2 - im(zn)^2.
         // im(z(n+1)) = im(c) + 2 * re(zn) * im(zn)

         __ Vmul(F32, q10, kZReal, kZImag);  // re(zn) * im(zn)

         __ Vmul(F32, kZReal, kZReal, kZReal);  // re(zn)^2
         __ Vadd(F32, kZReal, kCReal, kZReal);  // re(c) + re(zn)^2
         __ Vmls(F32, kZReal, kZImag, kZImag);  // re(c) + re(zn)^2 - im(zn)^2

         __ Vmov(F32, kZImag, kCImag);        // im(c)
         __ Vmls(F32, kZImag, q10, kNegTwo);  // im(c) + 2 * re(zn) * im(zn)

         __ Vmul(F32, q10, kZReal, kZReal);    // re(z(n+1))^2
         __ Vmla(F32, q10, kZImag, kZImag);    // re(z(n+1))^2 + im(z(n+1))^2
         __ Vcgt(F32, q10, q10, kModSqLimit);  // |z(n+1)|^2 > 4 ? ~0 : 0
         __ Vorr(F32, kFlags, kFlags, q10);    // (~0/0) | above result

         __ B(&iterative_formula_start);
         __ Bind(&iterative_formula_end);
       }

       // Narrow twice so that each mask is 8 bits, packed into
       // a single 32 bit register s4.
       // kLowerFlags is the lower half of kFlags, so the second narrow will
       // be working on the results of the first to halve the size of each
       // representation again.
       __ Vmovn(I32, kLowerFlags, kFlags);
       __ Vmovn(I16, kLowerFlags, kFlags);

       // '*' if in set, ' ' if not.
       __ Vbsl(Untyped32, kLowerFlags, kSpaces, kStars);

       // Add this to the string.
       __ Vst1(Untyped32,
               NeonRegisterList(kLowerFlags, 0),
               AlignedMemOperand(kWriteCursor, k32BitAlign, PostIndex));

       // Increase real part of c.
       __ Vadd(F32, kCReal, kCReal, kCRealStep);

       __ Subs(r5, r5, 1);
       __ B(ne, &c_real_loop);
     }

     // Put terminating character.
     __ Strb(kZero, MemOperand(kWriteCursor));

     // Print the string.
     __ Printf("%s\n", kStringPtr);

     // Increase imaginary part of c.
     __ Vadd(F32, kCImag, kCImag, kCImagStep);

     __ Subs(r4, r4, 1);
     __ B(ne, &c_imag_loop);
   }
   // Restore stack pointer.
   __ Add(sp, sp, kStringLength);
   // Restore register values.
   __ Pop(RegisterList(r4, r5, r6));
   __ Bx(lr);
 }

 #ifndef TEST_EXAMPLES
 int main() {
   MacroAssembler masm;
   // Generate the code for the example function.
   Label mandelbrot;
   masm.Bind(&mandelbrot);
   GenerateMandelBrot(&masm);
   masm.FinalizeCode();
 #ifdef VIXL_INCLUDE_SIMULATOR_AARCH32
   // There is no simulator defined for VIXL AArch32.
   printf("This example cannot be simulated\n");
 #else
   byte* code = masm.GetBuffer()->GetStartAddress<byte*>();
   uint32_t code_size = masm.GetSizeOfCodeGenerated();
   ExecutableMemory memory(code, code_size);
   // Run the example function.
   double (*mandelbrot_func)(uint32_t) =
       memory.GetEntryPoint<double (*)(uint32_t)>(mandelbrot,
                                                  masm.GetInstructionSetInUse());
   uint32_t iterations = 1000;
   (*mandelbrot_func)(iterations);
 #endif
   return 0;
 }
 #endif  // TEST_EXAMPLES
	// Copyright 2017, 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 GenerateMandelBrot(MacroAssembler* masm) {
	const QRegister kCReal = q0;
	const QRegister kCImag = q1;

	const QRegister kCRealStep = q13;
	const QRegister kCImagStep = q14;

	const QRegister kModSqLimit = q15;

	// Save register values.
	__ Push(RegisterList(r4, r5, r6));

	__ Vmov(F32, kCRealStep, 0.125);
	__ Vmov(F32, kCImagStep, 0.0625);

	const Register kZero = r2;
	__ Mov(kZero, 0);

	const DRegister kStars = d6;
	const DRegister kSpaces = d7;
	// Output characters - packed 4 characters into 32 bits.
	__ Vmov(I8, kStars, '*');
	__ Vmov(I8, kSpaces, ' ');

	const DRegisterLane kNegTwo = DRegisterLane(d7, 1);
	__ Vmov(s15, -2.0);

	// Imaginary part of c.
	__ Vdup(Untyped32, kCImag, kNegTwo);

	// Max modulus squared.
	__ Vmov(F32, kModSqLimit, 4.0);

	// Height of output in characters.
	__ Mov(r4, 64);

	// String length will be 129, so need 132 bytes of space.
	const uint32_t kStringLength = 132;

	// Make space for our string.
	__ Sub(sp, sp, kStringLength);

	// Set up a starting pointer for the string.
	const Register kStringPtr = r6;
	__ Mov(kStringPtr, sp);

	// Loop over imaginary values of c from -2 to 2, taking
	// 64 equally spaced values in the range.
	{
	Label c_imag_loop;

	__ Bind(&c_imag_loop);

	// Real part of c.
	// Store 4 equally spaced values in q0 (kCReal) to use SIMD.
	__ Vmov(s0, -2.0);
	__ Vmov(s1, -1.96875);
	__ Vmov(s2, -1.9375);
	__ Vmov(s3, -1.90625);

	// Width of output in terms of sets of 4 characters - twice that
	// of height to compensate for ratio of character height to width.
	__ Mov(r5, 32);

	const Register kWriteCursor = r3;
	// Set a cursor ready to write the next line.
	__ Mov(kWriteCursor, kStringPtr);

	// Loop over real values of c from -2 to 2, processing
	// 4 different values simultaneously using SIMD.
	{
	const QRegister kFlags = q2;
	const DRegister kLowerFlags = d4;

	Label c_real_loop;
	__ Bind(&c_real_loop);

	// Get number of iterations.
	__ Add(r1, r0, 1);

	// Perform the iterations of z(n+1) = zn^2 + c using SIMD.
	// If the result is that c is in the set, the element of
	// kFlags will be 0, else ~0.
	{
	const QRegister kZReal = q8;
	const QRegister kZImag = q9;

	// Real part of z.
	__ Vmov(F32, kZReal, 0.0);

	// Imaginary part of z.
	__ Vmov(F32, kZImag, 0.0);

	__ Vmov(F32, kFlags, 0.0);

	Label iterative_formula_start, iterative_formula_end;
	__ Bind(&iterative_formula_start);
	__ Subs(r1, r1, 1);
	__ B(le, &iterative_formula_end);

	// z(n+1) = zn^2 + c.
	// re(z(n+1)) = re(c) + re(zn)^2 - im(zn)^2.
	// im(z(n+1)) = im(c) + 2 * re(zn) * im(zn)

	__ Vmul(F32, q10, kZReal, kZImag); // re(zn) * im(zn)

	__ Vmul(F32, kZReal, kZReal, kZReal); // re(zn)^2
	__ Vadd(F32, kZReal, kCReal, kZReal); // re(c) + re(zn)^2
	__ Vmls(F32, kZReal, kZImag, kZImag); // re(c) + re(zn)^2 - im(zn)^2

	__ Vmov(F32, kZImag, kCImag); // im(c)
	__ Vmls(F32, kZImag, q10, kNegTwo); // im(c) + 2 * re(zn) * im(zn)

	__ Vmul(F32, q10, kZReal, kZReal); // re(z(n+1))^2
	__ Vmla(F32, q10, kZImag, kZImag); // re(z(n+1))^2 + im(z(n+1))^2
	__ Vcgt(F32, q10, q10, kModSqLimit); // \|z(n+1)\|^2 > 4 ? ~0 : 0
	__ Vorr(F32, kFlags, kFlags, q10); // (~0/0) \| above result

	__ B(&iterative_formula_start);
	__ Bind(&iterative_formula_end);
	}

	// Narrow twice so that each mask is 8 bits, packed into
	// a single 32 bit register s4.
	// kLowerFlags is the lower half of kFlags, so the second narrow will
	// be working on the results of the first to halve the size of each
	// representation again.
	__ Vmovn(I32, kLowerFlags, kFlags);
	__ Vmovn(I16, kLowerFlags, kFlags);

	// '*' if in set, ' ' if not.
	__ Vbsl(Untyped32, kLowerFlags, kSpaces, kStars);

	// Add this to the string.
	__ Vst1(Untyped32,
	NeonRegisterList(kLowerFlags, 0),
	AlignedMemOperand(kWriteCursor, k32BitAlign, PostIndex));

	// Increase real part of c.
	__ Vadd(F32, kCReal, kCReal, kCRealStep);

	__ Subs(r5, r5, 1);
	__ B(ne, &c_real_loop);
	}

	// Put terminating character.
	__ Strb(kZero, MemOperand(kWriteCursor));

	// Print the string.
	__ Printf("%s\n", kStringPtr);

	// Increase imaginary part of c.
	__ Vadd(F32, kCImag, kCImag, kCImagStep);

	__ Subs(r4, r4, 1);
	__ B(ne, &c_imag_loop);
	}
	// Restore stack pointer.
	__ Add(sp, sp, kStringLength);
	// Restore register values.
	__ Pop(RegisterList(r4, r5, r6));
	__ Bx(lr);
	}

	#ifndef TEST_EXAMPLES
	int main() {
	MacroAssembler masm;
	// Generate the code for the example function.
	Label mandelbrot;
	masm.Bind(&mandelbrot);
	GenerateMandelBrot(&masm);
	masm.FinalizeCode();
	#ifdef VIXL_INCLUDE_SIMULATOR_AARCH32
	// There is no simulator defined for VIXL AArch32.
	printf("This example cannot be simulated\n");
	#else
	byte* code = masm.GetBuffer()->GetStartAddress<byte*>();
	uint32_t code_size = masm.GetSizeOfCodeGenerated();
	ExecutableMemory memory(code, code_size);
	// Run the example function.
	double (*mandelbrot_func)(uint32_t) =
	memory.GetEntryPoint<double (*)(uint32_t)>(mandelbrot,
	masm.GetInstructionSetInUse());
	uint32_t iterations = 1000;
	(*mandelbrot_func)(iterations);
	#endif
	return 0;
	}
	#endif // TEST_EXAMPLES