1 files changed, 63 insertions, 0 deletions
diff --git a/src/tcl/bitsbytes.tcl b/src/tcl/bitsbytes.tcl
new file mode 100644
index 00000000..b1771b4b
--- /dev/null
+++ b/src/tcl/bitsbytes.tcl
@@ -0,0 +1,63 @@
+#----------------------------------------
+# Purpose - Create some $BIT variables
+#           Create $K and $M variables
+#          and some bit field extraction variables.
+# Creat helper variables ...
+#    BIT0.. BIT31
+
+for { set x 0  } { $x < 32 } { set x [expr $x + 1]} {
+    set vn [format "BIT%d" $x]
+    set $vn   [expr (1 << $x)]
+    global $vn
+
+}
+
+# Create K bytes values
+#    __1K ... to __2048K
+for { set x 1  } { $x < 2048 } { set x [expr $x * 2]} {
+    set vn [format "__%dK" $x]
+    set $vn   [expr (1024 * $x)]
+    global $vn
+}
+
+# Create M bytes values
+#    __1M ... to __2048K
+for { set x 1  } { $x < 2048 } { set x [expr $x * 2]} {
+    set vn [format "__%dM" $x] 
+    set $vn [expr (1024 * 1024 * $x)]
+    global $vn
+}
+
+proc create_mask { MSB LSB } {
+    return [expr (((1 << ($MSB - $LSB + 1))-1) << $LSB)]
+
+}
+
+# Cut Bits $MSB to $LSB out of this value.
+# Example: % format "0x%08x" [extract_bitfield 0x12345678 27 16]
+# Result:  0x02340000
+
+proc extract_bitfield { VALUE MSB LSB } {
+    return [expr [create_mask $MSB $LSB] & $VALUE]
+}
+
+
+# Cut bits $MSB to $LSB out of this value
+# and shift (normalize) them down to bit 0.
+#
+# Example: % format "0x%08x" [normalize_bitfield 0x12345678 27 16]
+# Result:  0x00000234
+#
+proc normalize_bitfield { VALUE MSB LSB } {
+    return [expr [extract_bitfield $VALUE $MSB $LSB ] >> $LSB]
+}
+
+proc show_normalize_bitfield { VALUE MSB LSB } {
+    set m [create_mask $MSB $LSB]
+    set mr [expr $VALUE & $m]
+    set sr [expr $mr >> $LSB]
+    puts [format "((0x%08x & 0x%08x) -> 0x%08x) >> %2d => (0x%x) %5d " $VALUE $m $mr $LSB $sr $sr]
+   return $sr
+}
+
+