avra: simplify OPRdRr

This allows us to remove a lot of labels usage in boot code. This
commit has no effect on forth.bin.

blk/204

@@ -8,3 +8,9 @@ byte that is taken care of. We still need to adjust by another
 byte before writing the offset.
 
 
+
+
+
+
+
+                                                        (cont.)

blk/205

@@ -0,0 +1,16 @@
+Structured flow
+
+z80a also has words that behave similarly to IF..THEN and
+BEGIN..UNTIL.
+
+On the IF side, we have IFZ, IFNZ, IFC, IFNC, and THEN,. When
+the opposite condition is met, a relative jump is made to
+THEN,'s PC. For example, if you have IFZ, a jump is made when
+Z is unset.
+
+On the BEGIN,..AGAIN, side, it's a bit different. You start
+with your BEGIN, instruction, and then later you issue a
+JRxx, instr followed by AGAIN,. Exactly like you would do
+with a label.
+
+                                                        (cont.)

blk/206

@@ -0,0 +1,3 @@
+On top of that, you have the very nice BREAK, instruction,
+which must also be preceeded by a JRxx, and will jump to the
+PC following the next AGAIN,

blk/246

@@ -1,13 +1,16 @@
 ( Place BEGIN, where you want to jump back and AGAIN after
   a relative jump operator. Just like BSET and BWR. )
 : BEGIN, PC ;
-: AGAIN, PC - 1- A, ;
-
 : BSET PC SWAP ! ;
-: BWR @ AGAIN, ;
 ( same as BSET, but we need to write a placeholder )
 : FJR, PC 0 A, ;
 : IFZ, JRNZ, FJR, ;
 : IFNZ, JRZ, FJR, ;
 : IFC, JRNC, FJR, ;
 : IFNC, JRC, FJR, ;
+: THEN,
+    DUP PC          ( l l pc )
+    -^ 1-           ( l off )
+    ( warning: l is a PC offset, not a mem addr! )
+    SWAP ORG @ + BIN( @ - ( off addr )
+    C! ;

blk/247

@@ -1,9 +1,8 @@
-: THEN,
-    DUP PC          ( l l pc )
-    -^ 1-           ( l off )
-    ( warning: l is a PC offset, not a mem addr! )
-    SWAP ORG @ + BIN( @ - ( off addr )
-    C!
-;
 : FWR BSET 0 A, ;
 : FSET @ THEN, ;
+: BREAK, FJR, 0x8000 OR ;
+: BREAK?, DUP 0x8000 AND IF
+        0x7fff AND 1 ALLOT THEN, -1 ALLOT
+    THEN ;
+: AGAIN, BREAK?, PC - 1- A, ;
+: BWR @ AGAIN, ;

blk/291

@@ -13,4 +13,4 @@ PC ORG @ 4 + ! ( find )
     NEG,
     A DECr,
 	( special case. zero len? we never find anything. )
-    JRZ, L1 FWR ( fail-B296 )                         ( cont. )
+    IFNZ, ( fail-B296 )                               ( cont. )

blk/293

@@ -1,16 +1,15 @@
-        JRNZ, L2 FWR ( loopend )
+        IFZ,
             ( match, let's compare the string then )
             DE DECss, ( Skip prev field. One less because we )
             DE DECss, ( pre-decrement )
             B C LDrr, ( loop C times )
-        BEGIN, ( loop )
+            BEGIN,
                 ( pre-decrement for easier Z matching )
                 DE DECss,
                 HL DECss,
                 LDA(DE),
                 (HL) CPr,
-            JRNZ, L3 FWR ( loopend )
-        DJNZ, AGAIN, ( loop )
-        L2 FSET L3 FSET ( loopend )
-
+                JRNZ, BREAK,
+            DJNZ, AGAIN,
+        THEN,
                                                       ( cont. )

blk/296

@@ -1,4 +1,4 @@
-    L1 FSET ( fail )
+    THEN, ( zero length check, B291 )
     A XORr,
     A INCr,
     L2 FSET ( end )

blk/328

@@ -2,15 +2,13 @@ CODE S=
     DE  POPqq,
     HL  POPqq,
     chkPS,
-    BEGIN, ( loop )
+    BEGIN,
         LDA(DE),
         (HL) CPr,
-        JRNZ, L1 FWR ( not equal? break early to "end".
-                       NZ is set. )
+        JRNZ, BREAK, ( not equal? break early. NZ is set. )
         A ORr,   ( if our char is null, stop )
         HL INCss,
         DE INCss,
-    JRNZ, AGAIN, ( loop )
-L1 FSET ( end )
+    JRNZ, AGAIN,
     PUSHZ,
 ;CODE

blk/662

@@ -1,5 +1,6 @@
 ( 0000 000d dddd 0000 )
-: OPRd CREATE , DOES> @ SWAP 4 LSHIFT OR A,, ;
+: _Rdp ( op rd -- op' place Rd ) 4 LSHIFT OR ;
+: OPRd CREATE , DOES> @ SWAP _Rdp A,, ;
 0b1001010000000101 OPRd ASR,   0b1001010000000000 OPRd COM,
 0b1001010000001010 OPRd DEC,   0b1001010000000011 OPRd INC,
 0b1001001000000110 OPRd LAC,   0b1001001000000101 OPRd LAS,

blk/663

@@ -1,9 +1,8 @@
 ( 0000 00rd dddd rrrr )
 : OPRdRr CREATE C, DOES> C@ ( rd rr op )
     OVER 0x10 AND 3 RSHIFT OR ( rd rr op' )
-    2 PICK 0x10 AND 4 RSHIFT OR ( rd rr op' )
     8 LSHIFT OR 0xff0f AND ( rd op' )
-    SWAP 0xf AND 4 LSHIFT OR A,, ;
+    SWAP _Rdp A,, ;
 0x1c OPRdRr ADC,   0x0c OPRdRr ADD,    0x20 OPRdRr AND,
 0x14 OPRdRr CP,    0x04 OPRdRr CPC,    0x10 OPRdRr CPSE,
 0x24 OPRdRr EOR,   0x2c OPRdRr MOV,    0x9c OPRdRr MUL,

blk/664

@@ -5,3 +5,9 @@
 0x70 OPRdK ANDI,   0x30 OPRdK CPI,     0x0e OPRdK LDI,
 0x60 OPRdK ORI,    0x40 OPRdK SBCI,    0x60 OPRdK SBR,
 0x50 OPRdK SUBI,
+
+( 0000 0000 AAAA Abbb )
+: OPAb CREATE C, DOES> C@ ( A b op )
+    ROT 3 LSHIFT ROT OR A, A, ;
+0x98 OPAb CBI,     0x9a OPAb SBI,      0x99 OPAb SBIC,
+0x9b OPAb SBIS,

blk/665

@@ -0,0 +1,11 @@
+: OPNA CREATE , DOES> @ A,, ;
+0x9598 OPNA BREAK, 0x9488 OPNA CLC,    0x94d8 OPNA CLH,
+0x94f8 OPNA CLI,   0x94a8 OPNA CLN,    0x94c8 OPNA CLS,
+0x94e8 OPNA CLT,   0x94b8 OPNA CLV,    0x9498 OPNA CLZ,
+0x9419 OPNA EIJMP, 0x9509 OPNA ICALL,  0x9519 OPNA EICALL,
+0x9409 OPNA IJMP,  0x0000 OPNA NOP,    0x9508 OPNA RET,
+0x9518 OPNA RETI,  0x9408 OPNA SEC,    0x9458 OPNA SEH,
+0x9478 OPNA SEI,   0x9428 OPNA SEN,    0x9448 OPNA SES,
+0x9468 OPNA SET,   0x9438 OPNA SEV,    0x9418 OPNA SEZ,
+0x9588 OPNA SLEEP, 0x95a8 OPNA WDR,
+