flash_test: Show printable characters along when read

So far flash read displayed data in hexadecimal format only.
Now additional ascii values are shown for printable
characters, which is common practice

Old format:

compat> flash 0 read 0x1d110100 0x20
Read 0x1d110100 + 32
  0x1d110100: 0x09 0x0f 0x00 0x6c 0x6f 0x67 0x2d 0x73
  0x1d110108: 0x74 0x6f 0x72 0x61 0x67 0x65 0x20 0xff

New format:

compat> flash 0 read 0x1d110100 0x20
Read 0x1d110100 + 32
  0x1d110100: 0x09 0x0f 0x00 0x6c 0x6f 0x67 0x2d 0x73  ...log-s
  0x1d110108: 0x74 0x6f 0x72 0x61 0x67 0x65 0x20 0xff  torage .

Signed-off-by: Jerzy Kasenberg <jerzy@apache.org>
Signed-off-by: Jerzy Kasenberg <jerzy.kasenberg@codecoup.pl>

test/flash_test/src/flash_test.c

@@ -26,6 +26,7 @@
 #include <shell/shell.h>
 #include <stdio.h>
 #include <string.h>
+#include <ctype.h>
 
 static int flash_cli_cmd(const struct shell_cmd *cmd, int argc, char **argv,
  struct streamer *streamer);
@@ -48,7 +49,6 @@ flash_cli_cmd(const struct shell_cmd *cmd, int argc, char **argv,
  int sec_cnt;
  int i;
  int devid;
- int soff;
  char *eptr;
  char tmp_buf[32];
  char pr_str[80];
@@ -157,21 +157,20 @@ flash_cli_cmd(const struct shell_cmd *cmd, int argc, char **argv,
  (long unsigned int) off);
  break;
  }
- for (i = 0, soff = 0; i < sec_cnt; i++) {
- soff += snprintf(pr_str + soff, sizeof(pr_str) - soff,
- "0x%02x ", tmp_buf[i] & 0xff);
- if (i % 8 == 7) {
- streamer_printf(streamer, " 0x%lx: %s\n",
- (long unsigned int) off, pr_str);
- soff = 0;
- off += 8;
+ for (i = 0; i < sec_cnt; i++) {
+ int n = i & 7;
+ if (n == 0) {
+ streamer_printf(streamer, " 0x%lx: ", (long unsigned int)off + i);
+ }
+ snprintf(pr_str + n * 5, 6, "0x%02x ", tmp_buf[i] & 0xff);
+ pr_str[41 + n] = isprint((uint8_t)tmp_buf[i]) ? tmp_buf[i] : '.';
+ if (n == 7 || i + 1 == sec_cnt) {
+ pr_str[41 + n + 1] = '\0';
+ memset(pr_str + (5 * n + 5), ' ', 5 * (7 - n) + 1);
+ streamer_printf(streamer, "%s\n", pr_str);
  }
  }
- if (i % 8) {
- streamer_printf(streamer, " 0x%lx: %s\n",
- (long unsigned int) off, pr_str);
- off += i;
- }
+ off += sec_cnt;
  }
  } else if (!strcmp(argv[2], "write")) {
  streamer_printf(streamer, "Write 0x%lx + %lx\n",