From 556ac27991e4810d3b37ff3e2e27e7ee43a49121 Mon Sep 17 00:00:00 2001
From: "Robin P. Clark" <r.clark@energytechnologycontrol.com>
Date: Sun, 9 Oct 2022 11:48:20 +0100
Subject: [PATCH] binary numbers not so trival in gawk

---
 binary_numbers.awk | 60 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 60 insertions(+)
 create mode 100644 binary_numbers.awk

diff --git a/binary_numbers.awk b/binary_numbers.awk
new file mode 100644
index 0000000..c351945
--- /dev/null
+++ b/binary_numbers.awk
@@ -0,0 +1,60 @@
+# gawk binary number functions
+# RPC 09OCT2022
+
+# convert an 8 bit binary number to an integer
+function bin_to_n(i)
+{
+    n = 0;
+    #printf(">> %s:", i);
+    for (k = 1; k < 9; k++) {
+        n = n * 2;
+        b = substr(i, k, 1);
+        if (b == "1") {
+            n = n + 1;
+        }
+    }
+    return (n);
+}
+
+# convert a number to a binary number
+function dectobin(n)
+{
+    printf("dectobin: n in %d ",n);
+    binstring = "0b"; # some c compilers allow 0bXXXXXXXX format numbers
+    bn = 128;
+    for(k=0;k<8;k++) {
+        if (n >= bn) {
+            binstring = binstring "1";
+            n = n - bn;
+        } else {
+            binstring = binstring "0"
+        }
+	printf(" bn %d",bn);
+	bn = bn / 2;
+    }
+    return binstring;
+}
+
+BEGIN {
+    FS = " ";
+
+    # gawk (I think) has no atoi() funciton or equiv. So a table of all 
+    # chars (well 256 ascii) can be used with the index function to get 
+    # round this
+    for (i = 0; i < 255; i++) {
+       table = sprintf("%s%c", table, i);
+    }
+}
+
+{
+	# assume on stdin a buffer of 8 bit binary numbers "01000001 01000010" is AB etc
+    for (i = 1; i <= NF; i++)
+        printf("bin-num#%d: %x --> %c\n", i, bin_to_n($i), bin_to_n($i));
+
+    s = "ABC123string to test";
+    for (i = 0; i < length(s); i++) {
+	nn = index(table, substr(s,i+1,1))-1;
+	printf("substr  :%s:%x:",ss,nn);
+        printf(" :%d: %s\n", i, dectobin(nn));
+    }
+}