collapseos/forth/z80a.fs
2020-03-30 14:05:07 -04:00

260 lines
3.8 KiB
Forth

( Z80 assembler )
( Splits word into msb/lsb, lsb being on TOS )
: SPLITB
256 /MOD SWAP
;
( To debug, change C, to .X )
: A, C, ;
7 CONSTANT A
0 CONSTANT B
1 CONSTANT C
2 CONSTANT D
3 CONSTANT E
4 CONSTANT H
5 CONSTANT L
6 CONSTANT (HL)
0 CONSTANT BC
1 CONSTANT DE
2 CONSTANT HL
3 CONSTANT AF
3 CONSTANT SP
( 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+- ;
: <<3 8 * ;
: <<4 16 * ;
( -- )
: OP1 CREATE C, DOES> C@ A, ;
0xeb OP1 EXDEHL,
0x76 OP1 HALT,
0xc9 OP1 RET,
0x17 OP1 RLA,
0x07 OP1 RLCA,
0x1f OP1 RRA,
0x0f OP1 RRCA,
0x37 OP1 SCF,
( r -- )
: OP1r
CREATE C,
DOES>
C@ ( r op )
SWAP ( op r )
<<3 ( op r<<3 )
OR A,
;
0x04 OP1r INCr,
0x05 OP1r DECr,
( r -- )
: OP1r0
CREATE C,
DOES>
C@ ( r op )
OR A,
;
0xa0 OP1r0 ANDr,
0xb0 OP1r0 ORr,
0xa8 OP1r0 XORr,
0xb8 OP1r0 CPr,
( 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,
: _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,
( 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,
;
( n -- )
: OP2n
CREATE C,
DOES>
C@ A, A,
;
0xd3 OP2n OUTnA,
0xdb OP2n INAn,
( 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,
( 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,
( 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,
( 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),
( ss -- )
: OP2ss
CREATE C,
DOES>
0xed A,
C@ SWAP ( op ss )
<<4 ( op ss<< 4 )
OR A,
;
0x4a OP2ss ADCHLss,
0x42 OP2ss SBCHLss,
( dd nn -- )
: OP3ddnn
CREATE C,
DOES>
C@ ( dd nn op )
ROT ( nn op dd )
<<4 ( nn op dd<<4 )
OR A,
SPLITB A, A,
;
0x01 OP3ddnn LDddnn,
( nn -- )
: OP3nn
CREATE C,
DOES>
C@ A,
SPLITB A, A,
;
0xcd OP3nn CALLnn,
0xc3 OP3nn JPnn,
0x22 OP3nn LD(nn)HL,
0x2a OP3nn LDHL(nn),
: OPJR
CREATE C,
DOES>
C@ A, 2 - A,
;
0x18 OPJR JRe,
0x38 OPJR JRCe,
0x30 OPJR JRNCe,
0x28 OPJR JRZe,
0x20 OPJR JRNZe,
0x10 OPJR DJNZe,
( Specials )
( dd nn -- )
: LDdd(nn),
0xed A,
SWAP <<4 0x4b OR A,
SPLITB A, A,
;
( nn dd -- )
: LD(nn)dd,
0xed A,
<<4 0x43 OR A,
SPLITB A, A,
;
( JTBL+18 == next )
: JPNEXT, [ JTBL 18 + LITN ] JPnn, ;
: CODE
( same as CREATE, but with native word )
(entry)
( JTBL+15 == next )
[ JTBL 15 + LITN ] ,
;
: ;CODE JPNEXT, ;
( Routines )
( JTBL+21 == next )
: chkPS, [ JTBL 21 + LITN ] CALLnn, ;