spi: spidev_test: Cleaned hexadecimal dump

#include <unistd.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <getopt.h>

#include <fcntl.h>

#include <sys/ioctl.h>

static uint32_t speed = 500000;

static uint16_t delay;

static void hex_dump(const void *src, size_t length, size_t line_size, char *prefix)

{

	int i = 0;

	const unsigned char *address = src;

	const unsigned char *line = address;

	unsigned char c;

	printf("%s | ", prefix);

	while (length-- > 0) {

		printf("%02X ", *address++);

		if (!(++i % line_size) || (length == 0 && i % line_size)) {

			if (length == 0) {

				while (i++ % line_size)

					printf("__ ");

			}

			printf(" | ");  /* right close */

			while (line < address) {

				c = *line++;

				printf("%c", (c < 33 || c == 255) ? 0x2E : c);

			}

			printf("\n");

			if (length > 0)

				printf("%s | ", prefix);

		}

	}

}

static void transfer(int fd)

{

	int ret;

	if (ret < 1)

		pabort("can't send spi message");

	for (ret = 0; ret < ARRAY_SIZE(tx); ret++) {

		if (!(ret % 6))

			puts("");

		printf("%.2X ", rx[ret]);

	}

	puts("");

	hex_dump(rx, ARRAY_SIZE(rx), 32, "RX");

}

static void print_usage(const char *prog)