/*********************************************************************************
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* Copyright: (C) 2023 LingYun IoT System Studio
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* All rights reserved.
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*
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* Filename: sht20.c
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* Description: This file is temperature and relative humidity sensor SHT20 code
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*
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* Version: 1.0.0(10/08/23)
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* Author: Guo Wenxue <guowenxue@gmail.com>
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* ChangeLog: 1, Release initial version on "10/08/23 17:52:00"
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*
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* Pin connection:
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* SHT20 Raspberry Pi 40Pin
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* VCC <-----> #Pin1(3.3V)
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* SDA <-----> #Pin3(SDA, BCM GPIO2)
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* SCL <-----> #Pin5(SCL, BCM GPIO3)
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* GND <-----> GND
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*
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* /boot/config.txt:
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* dtoverlay=i2c1,pins_2_3
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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 <string.h>
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#include <stdint.h>
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#include <string.h>
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#include <unistd.h>
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#include <libgen.h>
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#include <getopt.h>
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#include <time.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 <sys/types.h>
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#include <sys/stat.h>
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#include <linux/types.h>
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#include <linux/i2c.h>
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#include <linux/i2c-dev.h>
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/* SHT2X 7-bit I2C slave address */
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#define SHT2X_CHIPADDR 0x40
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/* SHT2X trigger command */
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#define SOFTRESET 0xFE
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#define TRIGGER_TEMPERATURE_NO_HOLD 0xF3
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#define TRIGGER_HUMIDITY_NO_HOLD 0xF5
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/* Linux /dev/i2c-x device program API mode */
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enum
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{
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MODE_IOCTL, /* I2C device API use ioctl() */
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MODE_RDWR, /* I2C device API use read()/write() */
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};
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typedef struct i2c_s
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{
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char *dev; /* I2C master device, /dev/i2c-N */
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int addr; /* 7-bits slave address */
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int fd; /* File description */
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int mode; /* I2C device API use read/write or ioctl mode */
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} i2c_t;
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int sht2x_softreset(i2c_t *i2c);
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int sht2x_get_serialnumber(i2c_t *i2c, uint8_t *serialnumber, int size);
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int sht2x_get_temp_humidity(i2c_t *i2c, float *temp, float *rh);
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int i2c_init(i2c_t *i2c, int mode, char *i2cdev, int addr);
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int i2c_write(i2c_t *i2c, uint8_t *data, int len);
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int i2c_read(i2c_t *i2c, uint8_t *buf, int size);
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void i2c_term(i2c_t *i2c);
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static inline void msleep(unsigned long ms);
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void print_buf(const char *prompt, uint8_t *buf, int size);
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void dump_buf(const char *prompt, char *buffer, size_t length);
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static inline void banner(const char *progname)
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{
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printf("%s program Version v1.0.0\n", progname);
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printf("Copyright (C) 2023 LingYun IoT System Studio.\n");
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}
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static void program_usage(const char *progname)
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{
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printf("Usage: %s [OPTION]...\n", progname);
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printf(" %s is SHT20 temperature and humidity sensor program. \n", progname);
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printf(" -d[device ] Specify I2C device, such as /dev/i2c-1\n");
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printf(" -m[mode ] Specify API mode, 0 for ioctl and 1 for read()/write()\n");
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printf(" -h[help ] Display this help information\n");
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printf(" -v[version ] Display the program version\n");
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printf("\n");
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banner(progname);
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return;
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}
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int main(int argc, char **argv)
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{
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char *dev="/dev/i2c-1";
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char *progname=NULL;
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int mode = MODE_IOCTL;
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int rv;
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float temp, rh;
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uint8_t serialnumber[8];
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i2c_t i2c;
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struct option long_options[] = {
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{"device", required_argument, NULL, 'd'},
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{"mode", required_argument, NULL, 'm'},
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{"version", no_argument, NULL, 'v'},
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{"help", no_argument, NULL, 'h'},
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{NULL, 0, NULL, 0}
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};
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progname = basename(argv[0]);
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/* Parser the command line parameters */
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while ((rv = getopt_long(argc, argv, "d:m:vh", long_options, NULL)) != -1)
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{
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switch (rv)
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{
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case 'd': /* Set I2C device path: /dev/i2c-1 */
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dev = optarg;
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break;
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case 'm': /* Set I2C API mode: 0,1 */
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mode = atoi(optarg) ? MODE_RDWR : MODE_IOCTL;
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break;
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case 'v': /* Get software version */
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banner(progname);
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return EXIT_SUCCESS;
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case 'h': /* Get help information */
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program_usage(progname);
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return 0;
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default:
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break;
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}
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}
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if( i2c_init(&i2c, mode, dev, SHT2X_CHIPADDR) < 0 )
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{
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printf("I2C master device initial failed.\n");
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return 1;
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}
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if( sht2x_softreset(&i2c) < 0 )
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{
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printf("SHT2x initialize failure, maybe device not present!\n");
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return 1;
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}
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if( sht2x_get_serialnumber(&i2c, serialnumber, 8) < 0)
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{
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printf("SHT2x get serial number failure\n");
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return 3;
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}
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if( sht2x_get_temp_humidity(&i2c, &temp, &rh) < 0 )
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{
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printf("SHT2x get get temperature and relative humidity failure\n");
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return 3;
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}
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printf("Temperature=%lf ℃ relative humidity=%lf.\n", temp, rh);
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i2c_term(&i2c);
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return 0;
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}
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int sht2x_softreset(i2c_t *i2c)
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{
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uint8_t buf[1];
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if( !i2c || i2c->fd<0 )
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{
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printf("%s line [%d] %s() get invalid input arguments\n", __FILE__, __LINE__, __func__ );
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return -1;
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}
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/* software reset SHT2x */
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buf[0] = SOFTRESET;
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if( i2c_write(i2c, buf, 1) < 0 )
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{
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return -2;
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}
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msleep(50);
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return 0;
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}
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int sht2x_get_temp_humidity(i2c_t *i2c, float *temp, float *rh)
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{
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uint8_t buf[4];
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if( !i2c || !temp || !rh || i2c->fd<0 )
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{
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printf("%s line [%d] %s() get invalid input arguments\n", __FILE__, __LINE__, __func__ );
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return -1;
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}
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/* send trigger temperature measure command and read the data */
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memset(buf, 0, sizeof(buf));
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buf[0]=TRIGGER_TEMPERATURE_NO_HOLD;
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i2c_write(i2c, buf, 1);
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msleep(85); /* datasheet: typ=66, max=85 */
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memset(buf, 0, sizeof(buf));
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i2c_read(i2c, buf, 3);
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print_buf("Temperature sample data: ", buf, 3);
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*temp = 175.72 * (((((int) buf[0]) << 8) + buf[1]) / 65536.0) - 46.85;
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/* send trigger humidity measure command and read the data */
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memset(buf, 0, sizeof(buf));
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buf[0] = TRIGGER_HUMIDITY_NO_HOLD;
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i2c_write(i2c, buf, 1);
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msleep(29); /* datasheet: typ=22, max=29 */
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memset(buf, 0, sizeof(buf));
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i2c_read(i2c, buf, 3);
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print_buf("Relative humidity sample data: ", buf, 3);
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*rh = 125 * (((((int) buf[0]) << 8) + buf[1]) / 65536.0) - 6;
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return 0;
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}
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int sht2x_get_serialnumber(i2c_t *i2c, uint8_t *serialnumber, int size)
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{
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uint8_t buf[4]={0x0};
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if( !i2c || i2c->fd<0 || !serialnumber || size!=8 )
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{
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printf("%s line [%d] %s() get invalid input arguments\n", __FILE__, __LINE__, __func__ );
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return -1;
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}
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/* Read SerialNumber from Location 1 */
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memset(buf, 0, sizeof(buf));
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buf[0] = 0xfa; /* command for readout on-chip memory */
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buf[1] = 0x0f; /* on-chip memory address */
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i2c_write(i2c, buf, 2);
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memset(buf, 0, sizeof(buf));
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i2c_read(i2c, buf, 4);
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if( !buf[0] && !buf[1] && !buf[2] && !buf[3] )
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{
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printf("ERROR: SHT2X device not detected!\n");
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return -2;
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}
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serialnumber[5]=buf[0]; /* Read SNB_3 */
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serialnumber[4]=buf[1]; /* Read SNB_2 */
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serialnumber[3]=buf[2]; /* Read SNB_1 */
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serialnumber[2]=buf[3]; /* Read SNB_0 */
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/* Read SerialNumber from Location 2 */
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memset(buf, 0, sizeof(buf) );
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buf[0]=0xfc; /* command for readout on-chip memory */
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buf[1]=0xc9; /* on-chip memory address */
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i2c_write(i2c, buf, 2);
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memset(buf, 0, sizeof(buf) );
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i2c_read(i2c, buf, 4);
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serialnumber[1]=buf[0]; /* Read SNC_1 */
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serialnumber[0]=buf[1]; /* Read SNC_0 */
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serialnumber[7]=buf[2]; /* Read SNA_1 */
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serialnumber[6]=buf[3]; /* Read SNA_0 */
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print_buf("SHT2x Serial number: ", serialnumber, 8);
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return 0;
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}
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/*+----------------------+
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*| I2C API functions |
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*+----------------------+*/
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int i2c_init(i2c_t *i2c, int mode, char *i2cdev, int addr)
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{
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if( !i2c || !i2cdev || !addr )
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return -1;
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memset(i2c, 0, sizeof(*i2c));
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i2c->addr = addr;
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i2c->dev = i2cdev;
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i2c->mode = mode;
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if( (i2c->fd=open(i2cdev, O_RDWR)) < 0)
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{
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printf("open i2c device %s failed: %s\n", i2cdev, strerror(errno));
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return -1;
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}
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if( MODE_RDWR == i2c->mode )
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{
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/* set I2C mode and SHT2x slave address */
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ioctl(i2c->fd, I2C_TENBIT, 0); /* Not 10-bit but 7-bit mode */
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ioctl(i2c->fd, I2C_SLAVE, i2c->addr); /* set SHT2x slave address */
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}
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return 0;
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}
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void i2c_term(i2c_t *i2c)
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{
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if( !i2c )
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return;
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if( i2c->fd > 0)
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close(i2c->fd);
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return ;
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}
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int i2c_write(i2c_t *i2c, uint8_t *data, int len)
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{
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struct i2c_rdwr_ioctl_data tr;
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int rv = 0;
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if( !data || len<= 0)
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{
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printf("%s() invalid input arguments!\n", __func__);
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return -1;
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}
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/* I2C device program API: read()/write() */
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if( MODE_RDWR == i2c->mode )
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{
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write(i2c->fd, data, len);
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return 0;
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}
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/* I2C device program API: ioctl() */
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tr.nmsgs = 1;
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tr.msgs = malloc( sizeof(struct i2c_msg)*tr.nmsgs );
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if ( !tr.msgs )
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{
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printf("%s() msgs malloc failed!\n", __func__);
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return -2;
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}
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tr.msgs[0].addr = i2c->addr;
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tr.msgs[0].flags = 0; //write
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tr.msgs[0].len = len;
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tr.msgs[0].buf = malloc(len);
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if( !tr.msgs[0].buf )
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{
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printf("%s() msgs malloc failed!\n", __func__);
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rv = -3;
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goto cleanup;
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}
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memcpy(tr.msgs[0].buf, data, len);
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if( ioctl(i2c->fd, I2C_RDWR, &tr)<0 )
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{
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printf("%s() ioctl failure: %s\n", __func__, strerror(errno));
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rv = -4;
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goto cleanup;
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}
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cleanup:
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if( tr.msgs[0].buf )
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free(tr.msgs[0].buf);
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if( tr.msgs )
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free(tr.msgs);
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return rv;
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}
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int i2c_read(i2c_t *i2c, uint8_t *buf, int size)
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{
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struct i2c_rdwr_ioctl_data tr;
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int rv = 0;
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if( !buf || size<= 0)
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{
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printf("%s() invalid input arguments!\n", __func__);
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return -1;
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}
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/* I2C device program API: read()/write() */
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if( MODE_RDWR == i2c->mode )
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{
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read(i2c->fd, buf, size);
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return 0;
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}
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/* I2C device program API: ioctl() */
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tr.nmsgs = 1;
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tr.msgs = malloc( sizeof(struct i2c_msg)*tr.nmsgs );
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if ( !tr.msgs )
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{
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printf("%s() msgs malloc failed!\n", __func__);
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return -2;
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}
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tr.msgs[0].addr = i2c->addr;
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tr.msgs[0].flags = I2C_M_RD; //read
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tr.msgs[0].len = size;
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tr.msgs[0].buf = buf;
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memset(buf, 0, size);
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if( ioctl(i2c->fd, I2C_RDWR, &tr)<0 )
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{
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printf("%s() ioctl failure: %s\n", __func__, strerror(errno));
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rv = -4;
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}
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free( tr.msgs );
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return rv;
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}
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/*+----------------------+
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*| Misc functions |
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*+----------------------+*/
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static inline void msleep(unsigned long ms)
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{
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struct timespec cSleep;
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unsigned long ulTmp;
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cSleep.tv_sec = ms / 1000;
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if (cSleep.tv_sec == 0)
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{
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ulTmp = ms * 10000;
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cSleep.tv_nsec = ulTmp * 100;
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}
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else
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{
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cSleep.tv_nsec = 0;
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}
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nanosleep(&cSleep, 0);
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}
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void print_buf(const char *prompt, uint8_t *buf, int size)
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{
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int i;
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if( !buf )
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{
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return ;
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}
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if( prompt )
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{
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printf("%s ", prompt);
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}
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for(i=0; i<size; i++)
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{
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printf("%02x ", buf[i]);
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}
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printf("\n");
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return ;
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}
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void dump_buf(const char *prompt, char *buffer, size_t length)
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{
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size_t i, j;
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if (prompt)
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{
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printf("%s\n", prompt);
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}
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for (i = 0; i < length; i += 16)
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{
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printf("%08zx: ", i);
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for (j = 0; j < 16; j++)
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{
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if (i + j < length)
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{
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printf("%02x ", buffer[i + j]);
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}
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else
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{
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printf(" ");
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}
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}
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printf(" ");
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for (j = 0; j < 16; j++)
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{
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if (i + j < length)
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{
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unsigned char c = buffer[i + j];
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printf("%c", (c >= 32 && c <= 126) ? c : '.');
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}
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else
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{
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printf(" ");
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}
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}
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printf("\n");
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}
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}
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