1 files changed, 90 insertions, 0 deletions
diff --git a/user/bin/hd.c b/user/bin/hd.c
new file mode 100644
index 0000000..4b5b81c
--- /dev/null
+++ b/user/bin/hd.c
@@ -0,0 +1,90 @@
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#define LINE_LEN 16
+
+int main(int argc, char **argv)
+{
+    int readfd = 0;
+    if (argc == 2)
+    {
+        readfd = open(argv[1], O_RDONLY, 0666);
+        if (readfd < 0)
+        {
+            fprintf(stderr, "open: %s\n", strerror(errno));
+            return 1;
+        }
+    }
+    else if (argc > 2)
+    {
+        printf("usage: hd [file]\n");
+        return 1;
+    }
+
+    char lastbuf[LINE_LEN];
+    char curbuf[LINE_LEN];
+    int off = 0;
+    int lastrep = 0;
+    int bytes;
+
+    int i;
+    while ((bytes = read(readfd, curbuf, LINE_LEN)) > 0)
+    {
+        if (off > 0 && !memcmp(lastbuf, curbuf, LINE_LEN))
+        {
+            if (!lastrep)
+            {
+                printf("*\n");
+                lastrep = 1;
+            }
+            off += bytes;
+            continue;
+        }
+        lastrep = 0;
+        printf("%08x  ", off);
+        off += bytes;
+        /* print bytes */
+        for (i = 0; i < LINE_LEN; ++i)
+        {
+            if (i < bytes)
+            {
+                printf("%02x ", (unsigned char)curbuf[i]);
+            }
+            else
+            {
+                printf("   ");
+            }
+            if (i == 7)
+            {
+                printf(" ");
+            }
+        }
+        /* show printable characters */
+        printf("|");
+        for (i = 0; i < bytes; ++i)
+        {
+            char c = curbuf[i];
+            if (c < 32 || c > 126)
+            {
+                printf(".");
+            }
+            else
+            {
+                printf("%c", c);
+            }
+        }
+        printf("|\n");
+        memcpy(lastbuf, curbuf, LINE_LEN);
+    }
+    printf("%08x\n", off);
+
+    if (readfd > 0)
+    {
+        close(readfd);
+    }
+    return 0;
+}