Express wacky shifts as the ARMARM says we should

Reinstate the check that an immediate value that doesn't use the preferred encoding is disassembled to #value,ror such that reassembling it would give you back the original op code.
Tested with a handful of values, plus inspected all duplicates possible in Excel.

Version 1.96. Tagged as 'Debugger-1_96'

VersionASM

@@ -11,13 +11,13 @@
                         GBLS    Module_HelpVersion
                         GBLS    Module_ComponentName
                         GBLS    Module_ComponentPath
-Module_MajorVersion     SETS    "1.95"
-Module_Version          SETA    195
+Module_MajorVersion     SETS    "1.96"
+Module_Version          SETA    196
 Module_MinorVersion     SETS    ""
 Module_Date             SETS    "24 Jul 2016"
 Module_ApplicationDate  SETS    "24-Jul-16"
 Module_ComponentName    SETS    "Debugger"
 Module_ComponentPath    SETS    "castle/RiscOS/Sources/Programmer/Debugger"
-Module_FullVersion      SETS    "1.95"
-Module_HelpVersion      SETS    "1.95 (24 Jul 2016)"
+Module_FullVersion      SETS    "1.96"
+Module_HelpVersion      SETS    "1.96 (24 Jul 2016)"
                         END

VersionNum

-/* (1.95)
+/* (1.96)
  *
  * This file is automatically maintained by srccommit, do not edit manually.
  * Last processed by srccommit version: 1.1.
  *
  */
-#define Module_MajorVersion_CMHG        1.95
+#define Module_MajorVersion_CMHG        1.96
 #define Module_MinorVersion_CMHG        
 #define Module_Date_CMHG                24 Jul 2016
 
-#define Module_MajorVersion             "1.95"
-#define Module_Version                  195
+#define Module_MajorVersion             "1.96"
+#define Module_Version                  196
 #define Module_MinorVersion             ""
 #define Module_Date                     "24 Jul 2016"
 
@@ -18,6 +18,6 @@
 #define Module_ComponentName            "Debugger"
 #define Module_ComponentPath            "castle/RiscOS/Sources/Programmer/Debugger"
 
-#define Module_FullVersion              "1.95"
-#define Module_HelpVersion              "1.95 (24 Jul 2016)"
-#define Module_LibraryVersionInfo       "1:95"
+#define Module_FullVersion              "1.96"
+#define Module_HelpVersion              "1.96 (24 Jul 2016)"
+#define Module_LibraryVersionInfo       "1:96"

s/ARM

@@ -1258,11 +1258,22 @@ Immediate
         BNE     %FT10
         TEQ     r2, #0                  ; but have a non-zero shift ?
         BNE     WackyShift
+        B       %FT20                   ; Unshifted 0-255
 10
-
-;Testing for weird shifts, ie representable numbers as <data><no shift> but are in fact <data><shift>
-;removed
-
+;Testing for weird shifts. There are 1023 duplicate immediates in total, of which 846 are >= 256.
+;
+;Since <data> is 8 bit, and <shift> is encoded divided by 2, there are at most 4 alternate encodings
+;for any immediate before the <data> value encodes some completely different number.
+;eg.     <data << 0><lowest_shift+0>   1  ROR 24 = 256
+;        <data << 2><lowest_shift+1>   4  ROR 26 = 256
+;        <data << 4><lowest_shift+2>   16 ROR 28 = 256
+;        <data << 6><lowest_shift+3>   64 ROR 30 = 256
+;
+;The <lowest_shift> is the preferred one per DDI 0406C, A5.2.4, so that's the one
+;whose <data> has at least one of bits 0-2 set.
+        TST     r4, #3
+        BEQ     WackyShift
+20
         CMPS    r8, #10
         BLO     Rem_Number              ; If really simple, just display number
                                         ; ie. 0..9 unambiguous