Copy z80a.fs to disk blocks

I don't remove z80a.fs yet because build process needs it, but that
will change shortly.

blk/001

@@ -2,6 +2,7 @@ MASTER INDEX
 
   3 Usage                      30 Dictionary
  70 Implementation notes      100 Block editor
+200 Z80 assembler
 
 
 

blk/200

@@ -0,0 +1,13 @@
+Z80 Assembler
+
+201 Guide                      208 Instructions list
+212 Loader                     213 Variables & consts
+215 Utils                      216 OP1
+218 OP1r                       220 OP1qq
+222 OP1rr                      224 OP2
+226 OP2n                       228 OP2rn
+230 OP2br                      232 OProt
+234 OP2r                       236 OP2ss
+238 OP3ddnn                    240 OP3nn
+242 Specials                   246 Flow
+

blk/201

@@ -0,0 +1,15 @@
+The following words allow you to assemble z80 binaries. Being
+Forth words, opcode assembly is a bit different than with a
+typical assembler. For example, what would traditionally be
+"ld a, b" would become "A B LDrr,".
+
+H@ offset at which we consider our PC 0. Used to compute PC. To
+have a proper PC, call  "H@ ORG !" at the beginning of your
+assembly process.
+
+Labels are a convenient way of managing relative jump
+calculations. Backward labels are easy. It is only a matter or
+recording "HERE" and do subtractions. Forward labels record the
+place where we should write the offset, and then when we get to
+that point later on, the label records the offset there.
+

blk/202

@@ -0,0 +1,13 @@
+To avoid using dict memory in compilation targets, we
+pre-declare label variables here, which means we have a limited
+number of it. For now, 4 ought to be enough.
+
+Flow
+
+There are 2 label types: backward and forward. For each type,
+there are two actions: set and write. Setting a label is
+declaring where it is. It has to be performed at the label's
+destination. Writing a label is writing its offset difference
+to the binary result. It has to be done right after a relative
+jump operation. Yes, labels are only for relative jumps.
+

blk/203

@@ -0,0 +1,14 @@
+For backward labels, set happens before write. For forward
+labels, write happen before set. The write operation writes a
+dummy placeholder, and then the set operation writes the offset
+at that placeholder's address.
+
+Variable actions are expected to be called with labels in
+front of them. Example, "L2 FSET"
+
+About that "1 -": z80 relative jumps record "e-2", that is,
+the offset that *counts the 2 bytes of the jump itself*.
+Because we set the label *after* the jump OP1 itself, that's 1
+byte that is taken care of. We still need to adjust by another
+byte before writing the offset.
+

blk/208

@@ -0,0 +1,16 @@
+Instructions list
+
+r => A B C D E H L (HL)
+ss/qq => BC DE HL AF/SP
+cc => CNZ CZ CNC CC CPO CPE CP CM
+
+LD [rr, rn, ddnn, (nn)HL, HL(nn), dd(nn), (nn)dd, rIXY, IXYr,
+    (DE)A, A(DE)]
+ADD [r, n, HLss, IXss, IXIX, IYss, IYIY]
+ADC [r, HLss]
+CP  [r]
+SBC [r, HLss]
+SUB [r, n]
+PUSH [qq]  POP [qq]
+INC [r, ss]            DEC [r, ss]
+AND [r, n] OR [r, n]   XOR [r, n]                       (cont.)

blk/209

@@ -0,0 +1,11 @@
+(cont.)
+OUT [nA, (C)r]         IN [An, r(C)]
+SET [br]   RES [br]    BIT [br]
+RL [r]     RLC [r]     SLA [r]     RLA         RLCA
+RR [r]     RRC [r]     SRL [r]     RRA         RRCA
+CALL [nn]  DJNZ
+JP [nn, (HL), (IX), (IY)]
+JR [, Z, NZ, C, NC]
+
+DI         EI          EXDEHL      EXX         HALT
+NOP        RET         SCF

blk/212

@@ -0,0 +1,8 @@
+( 59 == z80a's memory )
+H@ 0x59 RAM+ !
+10 ALLOT
+
+213 LOAD 215 LOAD 216 LOAD 217 LOAD 218 LOAD 220 LOAD 222 LOAD
+223 LOAD 224 LOAD 226 LOAD 228 LOAD 230 LOAD 232 LOAD 234 LOAD
+236 LOAD 238 LOAD 240 LOAD 242 LOAD 243 LOAD 244 LOAD 246 LOAD
+247 LOAD

blk/213

@@ -0,0 +1,9 @@
+: Z80AMEM+ 0x59 RAM+ @ + ;
+: ORG 0 Z80AMEM+ ;
+: L1 2 Z80AMEM+ ; : L2 4 Z80AMEM+ ;
+: L3 6 Z80AMEM+ ; : L4 8 Z80AMEM+ ;
+: A 7 ; : B 0 ; : C 1 ; : D 2 ;
+: E 3 ; : H 4 ; : L 5 ; : (HL) 6 ;
+: BC 0 ; : DE 1 ; : HL 2 ; : AF 3 ; : SP AF ;
+: CNZ 0 ; : CZ 1 ; : CNC 2 ; : CC 3 ;
+: CPO 4 ; : CPE 5 ; : CP 6 ; : CM 7 ;

blk/215

@@ -0,0 +1,16 @@
+( Splits word into msb/lsb, lsb being on TOS )
+: SPLITB
+    256 /MOD SWAP
+;
+: PC H@ ORG @ - ;
+( A, spits an assembled byte, A,, spits an assembled word
+  Both increase PC. To debug, change C, to .X )
+: A, C, ; : A,, SPLITB A, A, ;
+: <<3 8 * ;    : <<4 16 * ;
+( As a general rule, IX and IY are equivalent to spitting an
+  extra 0xdd / 0xfd and then spit the equivalent of HL )
+: IX 0xdd A, HL ; : IY 0xfd A, HL ;
+: _ix+- 0xff AND 0xdd A, (HL) ;
+: _iy+- 0xff AND 0xfd A, (HL) ;
+: IX+ _ix+- ; : IX- 0 -^ _ix+- ;
+: IY+ _iy+- ; : IY- 0 -^ _iy+- ;

blk/216

@@ -0,0 +1,10 @@
+: OP1 CREATE C, DOES> C@ A, ;
+0xf3 OP1 DI,                   0xfb OP1 EI,
+0xeb OP1 EXDEHL,               0xd9 OP1 EXX,
+0x76 OP1 HALT,                 0xe9 OP1 JP(HL),
+0x12 OP1 LD(DE)A,              0x1a OP1 LDA(DE),
+0x00 OP1 NOP,                  0xc9 OP1 RET,
+0x17 OP1 RLA,                  0x07 OP1 RLCA,
+0x1f OP1 RRA,                  0x0f OP1 RRCA,
+0x37 OP1 SCF,
+

blk/217

@@ -0,0 +1,11 @@
+( Relative jumps are a bit special. They're supposed to take
+  an argument, but they don't take it so they can work with
+  the label system. Therefore, relative jumps are an OP1 but
+  when you use them, you're expected to write the offset
+  afterwards yourself. )
+
+0x18 OP1 JR,                   0x10 OP1 DJNZ,
+0x38 OP1 JRC,                  0x30 OP1 JRNC,
+0x28 OP1 JRZ,                  0x20 OP1 JRNZ,
+
+

blk/218

@@ -0,0 +1,11 @@
+( r -- )
+: OP1r0
+    CREATE C,
+    DOES>
+    C@              ( r op )
+    OR A,
+;
+0x80 OP1r0 ADDr,               0x88 OP1r0 ADCr,
+0xa0 OP1r0 ANDr,               0xb8 OP1r0 CPr,
+0xb0 OP1r0 ORr,                0x90 OP1r0 SUBr,
+0x98 OP1r0 SBCr,               0xa8 OP1r0 XORr,

blk/220

@@ -0,0 +1,15 @@
+( qq -- also works for ss )
+: OP1qq
+    CREATE C,
+    DOES>
+    C@              ( qq op )
+    SWAP            ( op qq )
+    <<4             ( op qq<<4 )
+    OR A,
+;
+0xc5 OP1qq PUSHqq,             0xc1 OP1qq POPqq,
+0x03 OP1qq INCss,              0x0b OP1qq DECss,
+0x09 OP1qq ADDHLss,
+
+: ADDIXss, 0xdd A, ADDHLss, ;  : ADDIXIX, HL ADDIXss, ;
+: ADDIYss, 0xfd A, ADDHLss, ;  : ADDIYIY, HL ADDIYss, ;

blk/222

@@ -0,0 +1,14 @@
+: _1rr
+    C@              ( rd rr op )
+    ROT             ( rr op rd )
+    <<3             ( rr op rd<<3 )
+    OR OR A,
+;
+
+( rd rr )
+: OP1rr
+    CREATE C,
+    DOES>
+    _1rr
+;
+0x40 OP1rr LDrr,

blk/223

@@ -0,0 +1,13 @@
+( ixy+- HL rd )
+: LDIXYr,
+    ( dd/fd has already been spit )
+    LDrr,           ( ixy+- )
+    A,
+;
+
+( rd ixy+- HL )
+: LDrIXY,
+    ROT             ( ixy+- HL rd )
+    SWAP            ( ixy+- rd HL )
+    LDIXYr,
+;

blk/224

@@ -0,0 +1,7 @@
+: OP2 CREATE , DOES> @ 256 /MOD A, A, ;
+0xedb1 OP2 CPIR,
+0xed46 OP2 IM0,
+0xed56 OP2 IM1,
+0xed5e OP2 IM2,
+0xed44 OP2 NEG,
+0xed4d OP2 RETI,

blk/226

@@ -0,0 +1,13 @@
+( n -- )
+: OP2n
+    CREATE C,
+    DOES>
+    C@ A, A,
+;
+0xd3 OP2n OUTnA,
+0xdb OP2n INAn,
+0xc6 OP2n ADDn,
+0xe6 OP2n ANDn,
+0xf6 OP2n ORn,
+0xd6 OP2n SUBn,
+

blk/228

@@ -0,0 +1,11 @@
+( r n -- )
+: OP2rn
+    CREATE C,
+    DOES>
+    C@              ( r n op )
+    ROT             ( n op r )
+    <<3             ( n op r<<3 )
+    OR A, A,
+;
+0x06 OP2rn LDrn,
+

blk/230

@@ -0,0 +1,14 @@
+( b r -- )
+: OP2br
+    CREATE C,
+    DOES>
+    0xcb A,
+    C@              ( b r op )
+    ROT             ( r op b )
+    <<3             ( r op b<<3 )
+    OR OR A,
+;
+0xc0 OP2br SETbr,
+0x80 OP2br RESbr,
+0x40 OP2br BITbr,
+

blk/232

@@ -0,0 +1,16 @@
+( bitwise rotation ops have a similar sig )
+( r -- )
+: OProt
+    CREATE C,
+    DOES>
+    0xcb A,
+    C@              ( r op )
+    OR A,
+;
+0x10 OProt RLr,
+0x00 OProt RLCr,
+0x18 OProt RRr,
+0x08 OProt RRCr,
+0x20 OProt SLAr,
+0x38 OProt SRLr,
+

blk/234

@@ -0,0 +1,14 @@
+( cell contains both bytes. MSB is spit as-is, LSB is ORed
+  with r )
+( r -- )
+: OP2r
+    CREATE ,
+    DOES>
+    @ SPLITB SWAP   ( r lsb msb )
+    A,              ( r lsb )
+    SWAP <<3        ( lsb r<<3 )
+    OR A,
+;
+0xed41 OP2r OUT(C)r,
+0xed40 OP2r INr(C),
+

blk/236

@@ -0,0 +1,12 @@
+( ss -- )
+: OP2ss
+    CREATE C,
+    DOES>
+    0xed A,
+    C@ SWAP         ( op ss )
+    <<4             ( op ss<< 4 )
+    OR A,
+;
+0x4a OP2ss ADCHLss,
+0x42 OP2ss SBCHLss,
+

blk/238

@@ -0,0 +1,11 @@
+( dd nn -- )
+: OP3ddnn
+    CREATE C,
+    DOES>
+    C@              ( dd nn op )
+    ROT             ( nn op dd )
+    <<4             ( nn op dd<<4 )
+    OR A,
+    A,,
+;
+0x01 OP3ddnn LDddnn,

blk/240

@@ -0,0 +1,11 @@
+( nn -- )
+: OP3nn
+    CREATE C,
+    DOES>
+    C@ A,
+    A,,
+;
+0xcd OP3nn CALLnn,
+0xc3 OP3nn JPnn,
+0x22 OP3nn LD(nn)HL,
+0x2a OP3nn LDHL(nn),

blk/242

@@ -0,0 +1,16 @@
+( dd nn -- )
+: LDdd(nn),
+    0xed A,
+    SWAP <<4 0x4b OR A,
+    A,,
+;
+
+( nn dd -- )
+: LD(nn)dd,
+    0xed A,
+    <<4 0x43 OR A,
+    A,,
+;
+
+: JP(IX), IX DROP JP(HL), ;
+: JP(IY), IY DROP JP(HL), ;

blk/243

@@ -0,0 +1,14 @@
+( 26 == next )
+: JPNEXT, 26 JPnn, ;
+( 29 == chkPS )
+: chkPS, 29 CALLnn, ;
+
+: CODE
+    ( same as CREATE, but with native word )
+    (entry)
+    ( 23 == nativeWord )
+    23 C,
+;
+
+: ;CODE JPNEXT, ;
+

blk/244

@@ -0,0 +1,3 @@
+( Macros )
+( clear carry + SBC )
+: SUBHLss, A ORr, SBCHLss, ;

blk/246

@@ -0,0 +1,13 @@
+( 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, ;

blk/247

@@ -0,0 +1,9 @@
+: THEN,
+    DUP PC          ( l l pc )
+    -^ 1-           ( l off )
+    ( warning: l is a PC offset, not a mem addr! )
+    SWAP ORG @ +    ( off addr )
+    C!
+;
+: FWR BSET 0 A, ;
+: FSET @ THEN, ;

forth/z80a.fs

@@ -210,7 +210,7 @@
 0xdb OP2n INAn,
 0xc6 OP2n ADDn,
 0xe6 OP2n ANDn,
-0xf6 OP2n Orn,
+0xf6 OP2n ORn,
 0xd6 OP2n SUBn,
 
 ( r n -- )