z80: optimize chkPS

Inline it in next and make chkPS, call a newly reserved label for
it directly, removing a layer of indirection. This frees a spot in
the stable ABI.

blk/243

@@ -5,7 +5,7 @@
 
 : JPNEXT, 26 BJP, ; ( 26 == next )
 
-: chkPS, 29 BCALL, ; ( 29 == chkPS )
+: chkPS, L4 @ BCALL, ; ( chkPS, B305 )
 
 : CODE ( same as CREATE, but with native word )
     (entry)

blk/283

@@ -5,7 +5,7 @@ NOP,          ( 0a, unused )   0 JPnn,       ( 0b, cellWord )
 0 JPnn,   ( 0e, compiledWord ) 0 JPnn,       ( 11, pushRS )
 0 JPnn,       ( 14, popRS )
 EXDEHL, JP(HL), NOP, ( 17, nativeWord )
-0 JPnn,       ( 1a, next )     0 JPnn,       ( 1d, chkPS )
+0 JPnn,       ( 1a, next )     0 JPnn,       ( unused )
 NOP, NOP,   ( 20, numberWord ) NOP, NOP,     ( 22, litWord )
 NOP, NOP,     ( 24, addrWord ) NOP, NOP,     ( 26, unused )
 0 JPnn,       ( RST 28 )

blk/299

@@ -1,16 +0,0 @@
-L1 BSET PC ORG @ 0x1e + ! ( chkPS )
-( Note that you only need to call this in words that push
-  back to PSP. If they don't, calling chkPS is redundant with
-  check in next )
-    EXX,
-( We have the return address for this very call on the stack
-  and protected registers. 2 - is to compensate that. )
-    HL PS_ADDR 2 - LDddnn,
-    SP SUBHLss,
-    EXX,
-    CNC RETcc,      ( PS_ADDR >= SP? good )
-    JR, L2 BWR      ( abortUnderflow-B298 )
-
-
-
-

blk/300

@@ -3,14 +3,14 @@ PC ORG @ 0x1b + ! ( next )
   we jump to current IP, but we also take care of increasing
   it by 2 before jumping. )
 	( Before we continue: are stacks within bounds? )
-    L1 @ ( chkPS ) BCALL,
-    ( check RS )
-    IX PUSHqq, HL POPqq,
+    ( PS ) HL PS_ADDR LDddnn,
+    SP SUBHLss,
+    JRC, L2 BWR ( abortUnderflow-B298 )
+    ( RS ) IX PUSHqq, HL POPqq,
     DE RS_ADDR LDddnn,
     DE SUBHLss,
     JRC, L2 BWR ( IX < RS_ADDR? abortUnderflow-B298 )
     E 0 IY+ LDrIXY,
     D 1 IY+ LDrIXY,
-    IY INCss,
-    IY INCss,
+    IY INCss, IY INCss,
     ( continue to execute )

blk/305

@@ -1,15 +1,15 @@
-( Core words )
-( KEY and EMIT are not defined here. There're
-  expected to be defined in platform-specific code. )
-
-
-CODE EXECUTE
-    DE POPqq,
-    chkPS,
-    JR, L3 BWR      ( execute-B301 )
-
-
-
+L4 BSET ( chkPS )
+( Note that you only need to call this in words that push
+  back to PSP. If they don't, calling chkPS is redundant with
+  check in next )
+    EXX,
+( We have the return address for this very call on the stack
+  and protected registers. 2 - is to compensate that. )
+    HL PS_ADDR 2 - LDddnn,
+    SP SUBHLss,
+    EXX,
+    CNC RETcc,      ( PS_ADDR >= SP? good )
+    JR, L2 BWR      ( abortUnderflow-B298 )
 
 
 

blk/306

@@ -1,16 +1,16 @@
+( Core words )
+( KEY and EMIT are not defined here. There're
+  expected to be defined in platform-specific code. )
+
+CODE EXECUTE
+    DE POPqq,
+    chkPS,
+    JR, L3 BWR      ( execute-B301 )
+
 ( a b c -- b c a )
 CODE ROT
-    HL POPqq,       ( C )
-    DE POPqq,       ( B )
-    BC POPqq,       ( A )
+    HL POPqq, ( C ) DE POPqq, ( B ) BC POPqq, ( A )
     chkPS,
-    DE PUSHqq,      ( B )
-    HL PUSHqq,      ( C )
-    BC PUSHqq,      ( A )
+    DE PUSHqq, ( B ) HL PUSHqq, ( C ) BC PUSHqq, ( A )
 ;CODE
 
-
-
-
-
-