63 lines
2.6 KiB
Plaintext
63 lines
2.6 KiB
Plaintext
/*
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* Copyright Ana Balevic, 2008-2009. All rights reserved.
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*/
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#ifndef _PABIO_KERNEL2_H_
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#define _PABIO_KERNEL2_H_
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#include "parameters.h"
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/* PARALLEL PUT BITS IMPLEMENTATION (CUDA1.1+ compatible)
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* Set numbits in the destination word out[kc] starting from the position startbit
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* Implementation comments:
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* Second atomic operation actually sets these bits to the value stored in the codeword; the other bits are left unotuched
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* First atomic operation is a necessary prepration - we change only the bits that will be affected by the codeword to be written to 1s
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* in order for set bits to work with using atomicand.
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* TODOs: benchmark performance 1) gm atomics vs sm atomics; 2) memset at init time vs. atomicOr
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*/
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__device__ void static put_bits_atomic2(unsigned int* out, unsigned int kc,
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unsigned int startbit, unsigned int numbits,
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unsigned int codeword) {
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unsigned int cw32 = codeword;
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unsigned int restbits = 32-startbit-numbits;
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/* 1. Prepare the memory location */
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#ifndef MEMSET0 //Can remove this part if the contents of the memory are already set to all 0s
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unsigned int mask = ((1<<numbits)-1); // -> 0000...001111
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mask<<=restbits; //fill in zeros at the back positions -> 0000...001111000 -> 11111110000111111111111 (in order not to and other positions)
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atomicAnd(&out[kc], ~mask); //set 0s in the destination from startbit in the len of numbits
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#endif
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/* 2. Write the codeword */
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cw32 = cw32<<restbits;
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atomicOr(&out[kc], cw32);
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}
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/* PARALLEL PUT BITS IMPLEMENTATION (CUDA1.1+ compatible)
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* Checkes if the part of the word to be written matches whole memory location, and if yes, avoids using the atmoics.
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* Experience: no benefits, even a bit slower on CUDA.
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*/
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__device__ void static put_bits_atomic2a(unsigned int* out, unsigned int kc,
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unsigned int startbit, unsigned int numbits,
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unsigned int codeword) {
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unsigned int cw32 = codeword;
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unsigned int restbits = 32-startbit-numbits;
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/* 1. Prepare the memory location */
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#ifndef MEMSET0 //Can remove this part if the contents of the memory are already set to all 0s
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unsigned int mask = ((1<<numbits)-1); // -> 0000...001111
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mask<<=restbits; //fill in zeros at the back positions -> 0000...001111000 -> 11111110000111111111111 (in order not to and other positions)
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atomicAnd(&out[kc], ~mask); //set 0s in the destination from startbit in the len of numbits
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#endif
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/* 2. Write the codeword */
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if (startbit == 0 && restbits == 0) {
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out[kc] = cw32;
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} else {
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cw32 = cw32<<restbits;
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atomicOr(&out[kc], cw32);
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}
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}
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#endif //ifndef _PABIO_KERNEL_H_
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