Add support for local colour tables in GIFs

ChangeFSI previously only supported global colour tables, but will now look at the local colour table bit too.
Additionally, the info report was looking at the wrong bitfield when describing the log2bpp - always showing 8 (because it was showing the colour table size).

Version 1.39. Tagged as 'ChangeFSI-1_39'

VersionNum

-/* (1.38)
+/* (1.39)
  *
  * This file is automatically maintained by srccommit, do not edit manually.
  * Last processed by srccommit version: 1.1.
  *
  */
-#define Module_MajorVersion_CMHG        1.38
+#define Module_MajorVersion_CMHG        1.39
 #define Module_MinorVersion_CMHG        
-#define Module_Date_CMHG                12 May 2013
+#define Module_Date_CMHG                15 Jul 2013
 
-#define Module_MajorVersion             "1.38"
-#define Module_Version                  138
+#define Module_MajorVersion             "1.39"
+#define Module_Version                  139
 #define Module_MinorVersion             ""
-#define Module_Date                     "12 May 2013"
+#define Module_Date                     "15 Jul 2013"
 
-#define Module_ApplicationDate          "12-May-13"
+#define Module_ApplicationDate          "15-Jul-13"
 
 #define Module_ComponentName            "ChangeFSI"
 #define Module_ComponentPath            "mixed/RiscOS/Sources/Apps/ChangeFSI"
 
-#define Module_FullVersion              "1.38"
-#define Module_HelpVersion              "1.38 (12 May 2013)"
-#define Module_LibraryVersionInfo       "1:38"
+#define Module_FullVersion              "1.39"
+#define Module_HelpVersion              "1.39 (15 Jul 2013)"
+#define Module_LibraryVersionInfo       "1:39"

source/ChangeFSI

@@ -2181,9 +2181,11 @@ DEF FNChangeFSI(A$,spritearea%,workspace%,worklimit%,oksave%,okinfo%,RETURN ram%
       GIF=BGET#c%
       GIFback=BGET#c%
       GIFext=BGET#c%
-      quant%=(GIF AND 7)+1
+      quant%=((GIF>>4)AND 7)+1:REM Log2bpp
       IF GIF AND &80 THEN
-        FOR C%=0 TO (1<<quant%)-1
+        REM Have global colour table
+        I%=1<<((GIF AND 7)+1)
+        FOR C%=0 TO I%-1
           r%(C%)=BGET#c%/255*F
           g%(C%)=BGET#c%/255*F
           b%(C%)=BGET#c%/255*F
@@ -2201,7 +2203,7 @@ DEF FNChangeFSI(A$,spritearea%,workspace%,worklimit%,oksave%,okinfo%,RETURN ram%
         UNTIL GIFgcesz=0
         I%=BGET#c%
       ENDWHILE
-      IF I%<>ASC "," ERROR 42,"GIF file without , in right place"
+      IF I%<>ASC "," ERROR 42,"GIF without image separator in right place"
       REM pixel aspect ratio
       IF GIFext<>0 AND GIFext<>49 THEN
         IF GIFext>49 THEN
@@ -2214,7 +2216,7 @@ DEF FNChangeFSI(A$,spritearea%,workspace%,worklimit%,oksave%,okinfo%,RETURN ram%
         ENDIF
       ENDIF
       GIFleft=FNHW
-      GIFright=FNHW
+      GIFtop=FNHW
       sx%=FNHW
       sy%=FNHW
       IF GIFsx<sx% OR GIFsy<sy% THEN
@@ -2227,7 +2229,16 @@ DEF FNChangeFSI(A$,spritearea%,workspace%,worklimit%,oksave%,okinfo%,RETURN ram%
         ENDIF
       ENDIF
       GIF=BGET#c%
-      IF GIF AND &40 flag=501:r$="FN8"
+      IF GIF AND &40 flag=501:r$="FN8":REM Interlaced
+      IF GIF AND &80 THEN
+        REM Have local colour table, takes precedence
+        I%=1<<((GIF AND 7)+1)
+        FOR C%=0 TO I%-1
+          r%(C%)=BGET#c%/255*F
+          g%(C%)=BGET#c%/255*F
+          b%(C%)=BGET#c%/255*F
+        NEXT
+      ENDIF
       setcodes%=BGET#c%
       clearcode%=1<<setcodes%
       st%=PTR#c%