119 lines
3.3 KiB
C
119 lines
3.3 KiB
C
/*
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* spiSpeed.c:
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* Code to measure the SPI speed/latency.
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* Copyright (c) 2014 Gordon Henderson
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***********************************************************************
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* This file is part of wiringPi:
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* https://projects.drogon.net/raspberry-pi/wiringpi/
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*
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* wiringPi is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as
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* published by the Free Software Foundation, either version 3 of the
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* License, or (at your option) any later version.
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*
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* wiringPi is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with wiringPi.
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* If not, see <http://www.gnu.org/licenses/>.
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***********************************************************************
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <stdint.h>
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#include <string.h>
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#include <errno.h>
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//#include <fcntl.h>
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//#include <sys/ioctl.h>
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//#include <linux/spi/spidev.h>
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#include <wiringPi.h>
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#include <wiringPiSPI.h>
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#define TRUE (1==1)
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#define FALSE (!TRUE)
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#define SPI_CHAN 0
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#define NUM_TIMES 100
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#define MAX_SIZE (1024*1024)
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static int myFd ;
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void spiSetup (int speed)
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{
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if ((myFd = wiringPiSPISetup (SPI_CHAN, speed)) < 0)
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{
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fprintf (stderr, "Can't open the SPI bus: %s\n", strerror (errno)) ;
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exit (EXIT_FAILURE) ;
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}
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}
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int main (void)
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{
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int speed, times, size ;
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unsigned int start, end ;
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int spiFail ;
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unsigned char *myData ;
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double timePerTransaction, perfectTimePerTransaction, dataSpeed ;
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if ((myData = malloc (MAX_SIZE)) == NULL)
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{
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fprintf (stderr, "Unable to allocate buffer: %s\n", strerror (errno)) ;
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exit (EXIT_FAILURE) ;
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}
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wiringPiSetup () ;
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for (speed = 1 ; speed <= 32 ; speed *= 2)
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{
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printf ("+-------+--------+----------+----------+-----------+------------+\n") ;
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printf ("| MHz | Size | mS/Trans | TpS | Mb/Sec | Latency mS |\n") ;
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printf ("+-------+--------+----------+----------+-----------+------------+\n") ;
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spiFail = FALSE ;
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spiSetup (speed * 1000000) ;
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for (size = 1 ; size <= MAX_SIZE ; size *= 2)
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{
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printf ("| %5d | %6d ", speed, size) ;
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start = millis () ;
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for (times = 0 ; times < NUM_TIMES ; ++times)
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if (wiringPiSPIDataRW (SPI_CHAN, myData, size) == -1)
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{
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printf ("SPI failure: %s\n", strerror (errno)) ;
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spiFail = TRUE ;
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break ;
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}
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end = millis () ;
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if (spiFail)
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break ;
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timePerTransaction = ((double)(end - start) / (double)NUM_TIMES) / 1000.0 ;
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dataSpeed = (double)(size * 8) / (1024.0 * 1024.0) / timePerTransaction ;
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perfectTimePerTransaction = ((double)(size * 8)) / ((double)(speed * 1000000)) ;
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printf ("| %8.3f ", timePerTransaction * 1000.0) ;
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printf ("| %8.1f ", 1.0 / timePerTransaction) ;
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printf ("| %9.5f ", dataSpeed) ;
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printf ("| %8.5f ", (timePerTransaction - perfectTimePerTransaction) * 1000.0) ;
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printf ("|\n") ;
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}
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close (myFd) ;
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printf ("+-------+--------+----------+----------+-----------+------------+\n") ;
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printf ("\n") ;
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}
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return 0 ;
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}
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