parse: use "0<" instead of "0 <"

As I wrote in my "Clarify signed-ness" commit, "0 <" is broken.

Also, made this unit a bit more compact. The RC2014 stage1 can
really use some breathing room...

blk/018

@@ -5,7 +5,7 @@ unsigned. For convenience, decimal parsing and formatting
 support the "-" prefix, but under the hood, it's all unsigned.
 
 This leads to some oddities. For example, "-1 0 <" is false.
-To compare whether something is negative, use the "<0" word
+To compare whether something is negative, use the "0<" word
 which is the equivalent to "0x7fff >".
 
 

forth/cmp.fs

@@ -2,8 +2,7 @@
 
 : >= < NOT ;
 : <= > NOT ;
-: <0 32767 > ;
+: 0>= 0< NOT ;
-: >=0 <0 NOT ;
 
 ( n1 -- n1 true )
 : <>{ 1 ;

forth/fmt.fs

@@ -12,7 +12,7 @@
 
 : .               ( n -- )
     ( handle negative )
-    DUP <0 IF '-' EMIT -1 * THEN
+    DUP 0< IF '-' EMIT -1 * THEN
     _
     BEGIN
     DUP '9' > IF DROP EXIT THEN  ( stop indicator, we're done )

forth/icore.fs

@@ -51,6 +51,7 @@
 : = CMP NOT ;
 : < CMP -1 = ;
 : > CMP 1 = ;
+: 0< 32767 > ;
 
 ( r c -- r f )
 ( Parse digit c and accumulate into result r.
@@ -61,7 +62,7 @@
     ( parse char )
     '0' -
     ( if bad, return "r -1" )
-    DUP 0 < IF DROP -1 EXIT THEN   ( bad )
+    DUP 0< IF DROP -1 EXIT THEN    ( bad )
     DUP 9 > IF DROP -1 EXIT THEN   ( bad )
     ( good, add to running result )
     SWAP 10 * +                    ( r*10+n )

forth/parse.fs

@@ -11,14 +11,14 @@
 ;
 
 ( returns negative value on error )
-: hexdig            ( c -- n )
+: _            ( c -- n )
     ( '0' is ASCII 48 )
     48 -
-    DUP 0 < IF EXIT THEN                ( bad )
+    DUP 0< IF EXIT THEN                 ( bad )
     DUP 10 < IF EXIT THEN               ( good )
     ( 'a' is ASCII 97. 59 = 97 - 48 )
     49 -
-    DUP 0 < IF EXIT THEN                ( bad )
+    DUP 0< IF EXIT THEN                 ( bad )
     DUP 6 < IF 10 + EXIT THEN           ( good )
     ( bad )
     255 -
@@ -31,24 +31,23 @@
     2+
     ( validate slen )
     DUP SLEN                            ( a l )
-    DUP 0 = IF DROP 0 EXIT THEN         ( a 0 )
+    DUP NOT IF DROP 0 EXIT THEN         ( a 0 )
     4 > IF DROP 0 EXIT THEN             ( a 0 )
-    0 ( a r )
+    0  ( a r )
     BEGIN
-    OVER C@
+    SWAP C@+                            ( r a+1 c )
-    DUP 0 = IF DROP SWAP DROP 1 EXIT THEN ( r, 1 )
+    DUP NOT IF 2DROP 1 EXIT THEN        ( r, 1 )
-    hexdig                              ( a r n )
+    _                                   ( r a n )
-    DUP 0 < IF DROP DROP 1 EXIT THEN    ( a 0 )
+    DUP 0< IF ROT 2DROP 0 EXIT THEN     ( a 0 )
-    SWAP 16 * +                         ( a r*16+n )
+    ROT 16 * +                          ( a r*16+n )
-    SWAP 1+ SWAP                        ( a+1 r )
     AGAIN
 ;
 
 ( returns negative value on error )
-: bindig            ( c -- n )
+: _            ( c -- n )
     ( '0' is ASCII 48 )
     48 -
-    DUP 0 < IF EXIT THEN                ( bad )
+    DUP 0< IF EXIT THEN                 ( bad )
     DUP 2 < IF EXIT THEN                ( good )
     ( bad )
     255 -
@@ -65,12 +64,11 @@
     16 > IF DROP 0 EXIT THEN            ( a 0 )
     0 ( a r )
     BEGIN
-    OVER C@
+    SWAP C@+                               ( r a+1 c )
-    DUP 0 = IF DROP SWAP DROP 1 EXIT THEN ( r, 1 )
+    DUP NOT IF 2DROP 1 EXIT THEN           ( r 1 )
-    bindig                              ( a r n )
+    _                                      ( r a n )
-    DUP 0 < IF DROP DROP 1 EXIT THEN    ( a 0 )
+    DUP 0< IF ROT 2DROP 0 EXIT THEN        ( a 0 )
-    SWAP 2 * +                          ( a r*2+n )
+    ROT 2 * +                              ( a r*2+n )
-    SWAP 1+ SWAP                        ( a+1 r )
     AGAIN
 ;