Position printing and editing

hex.c

@@ -1,35 +1,40 @@
 #include <stdio.h>
 #include <ctype.h>
 
-// TODO: ASCII/Position printing 
+// TODO: Position printing 
 // TODO: Stop appending garbage at file end
-// TODO: Simplify/clean some code (useless condition/loop guard brackets)
+// TODO: Skip repeating lines
+// TODO: Coloring printable ASCII characters in output
+// TODO: Stop scanning always for cmd & loc (for q and s commands)
 
 #define BYTES 1024
 #define BYTES_PER_LINE 20
 
-void print_hex(unsigned char* buf, int byteno)
-{ 
+void print_hex(unsigned char* buf, int byteno, int pos)
+{
   for (int i=0; i<byteno; i++)
   {
+    // Print line number here
     if (i % BYTES_PER_LINE == 0)
     {
+      //printf("%03d:  ", lineno);
       if (i != 0)
       {
         printf("  ");
         for (int j=i-BYTES_PER_LINE; j<i; j++)
         {
-          if (isprint(buf[j])) 
-          {
-            printf("%c", buf[j]);
-          }
-          else {
-            printf(".");    
-          }
+          if (isprint(buf[j])) printf("%c", buf[j]);
+          else printf(".");
         }
       }
       puts("");
+      // Here, we could print positions in hex but I prefer using integers.
+      //printf("%04X  ", i);
+      
+      if (pos == 0) printf("%06d:   ", i);
+      else printf("%06d:   ", pos);
     }
+
     printf("%.2X ", buf[i]);
   }
 
@@ -37,10 +42,7 @@ void print_hex(unsigned char* buf, int byteno)
   int padding = BYTES_PER_LINE - (byteno % BYTES_PER_LINE);
   if (padding < BYTES_PER_LINE)
   {
-    for (int i=0; i<padding; i++)
-    {
-      printf("   ");
-    }
+    for (int i=0; i<padding; i++) printf("   ");
     printf("  ");
   }
 
@@ -61,25 +63,26 @@ int main(int argc, char** argv)
 {
   if (argc != 2)
   {
-    printf("Usage: %s <file>\n", argv[0]);
+    printf("Usage: %s <file>\nInline commands:\n\tpX - print position X\n\teX - edit position X\n\ts  - save modified buffer\n\tq  - quit\n", argv[0]);
     return -1;
   }
 
   FILE* f = fopen(argv[1], "r");
   unsigned char buf[BYTES];
   int byteno = fread(buf, 1, BYTES, f);
-  print_hex(buf, byteno);
+  print_hex(buf, byteno, 0);
   
   for (;;)
   {
     char cmd;
-    int loc = 0;
+    int loc;
+     
     scanf("%c%d", &cmd, &loc);
     switch(cmd)
     {
       case 'p':
       case 'P':
-        print_hex(buf + loc, BYTES_PER_LINE);
+        print_hex(buf + loc, BYTES_PER_LINE, loc);
         break;
       case 'e':
       case 'E':
@@ -99,7 +102,6 @@ int main(int argc, char** argv)
       case 'q':
       case 'Q':
         return 0;
-        break;
     }
   }
 }

test.txt

@@ -1,3 +1,3 @@
-=ello, from a text file.
+?ello, from a text file.
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