/*
* Copyright (c) 2017 International Characters.
* This software is licensed to the public under the Open Software License 3.0.
*/
#ifndef SWIZZLE_H
#define SWIZZLE_H
#include "kernel.h"
namespace IDISA { class IDISA_Builder; }
// The SwizzleGenerator class creates a kernel that transforms a set of bit streams into a swizzled form.
// In swizzled form, one "swizzle field" each from a set of streams are grouped together to be processed
// as a unit using SIMD operations. For example, for a swizzle field width of 64 and a block size of 256,
// 4 streams are swizzled together to be operated on as a group. The ratio of the block size to the
// swizzle field size is known as the swizzle factor, in this case 4.
// Swizzled form is convenient for performing sequential operations on parallel sets of streams,
// such as compression of each swizzle field by known counts, or stitching together known numbers
// of bits from two different sources.
// Any number of bit streams may be swizzled together. However, the outputSets are always
// grouped together in multiples of the swizzle factor. If the bit stream count is not
// an exact multiple of the swizzle factor, null streams (all zero bits) are added for
// each swizzle group.
// The input streams may come from any number of parallel input sets, each of the same size.
// The number of inputSets defaults to 1.
// The output streams may be separated in a number of output sets. However, output streams
// sets must be a multiple of the swizzle factor size.
// For example: consider the following 4 streams (32 bits each)
// Stream 1: 000pomnl 000000kj 00000ihg 00fedcba
// Stream 2: 00065432 0000001z 00000yxw 00vutsrq
// Stream 3: 000POMNL 000000KJ 00000IHG 00FEDCBA
// Stream 4: 00065432 0000001Z 00000YXW 00VUTSRQ
//
// The swizzled output using a field width of 8 produces the following swizzles.
//
// Swizzle 1: 00VUTSRQ 00FEDCBA 00vutsrq 00fedcba
// Swizzle 2: 00000YXW 00000IHG 00000yxw 00000ihg
// Swizzle 3: 0000001Z 000000KJ 0000001z 000000kj
// Swizzle 4: 00065432 000POMNL 00065432 000pomnl
//
// Now it might be convenient to compress all fields of swizzle 1 by 2, all fields of swizzle 2 by 5
// and so on.
//
namespace kernel {
class SwizzleGenerator : public BlockOrientedKernel {
public:
SwizzleGenerator(const std::unique_ptr & iBuilder, unsigned bitStreamCount, unsigned outputSets = 1, unsigned inputSets = 1, unsigned fieldWidth = 64);
protected:
void generateDoBlockMethod(const std::unique_ptr & iBuilder) override;
private:
const unsigned mBitStreamCount;
const unsigned mFieldWidth;
const unsigned mSwizzleFactor;
const unsigned mInputSets;
const unsigned mOutputSets;
};
}
#endif