collapseos/blk/603

( Computes n into crc c with polynomial 0x1021 )
CODE _crc16  ( c n -- c ) EXX, ( protect BC )
    HL POP, ( n ) DE POP, ( c )
    A L LDrr, D XORr, D A LDrr,
    B 8 LDri,
    BEGIN,
        E SLA, D RL,
        IFC, ( msb is set, apply polynomial )
            A D LDrr, 0x10 XORi, D A LDrr,
            A E LDrr, 0x21 XORi, E A LDrr,
        THEN,
    DJNZ, AGAIN,
    DE PUSH,
EXX, ( unprotect BC ) ;CODE
sdc: implement _crc16 in z80 2020-04-25 10:46:01 +10:00			`( Computes n into crc c with polynomial 0x1021 )`
z80: Use BC as IP register instead of IY It's a bit more inconvenient in terms of register protection (BC is much more generally useful than IY), but it makes tight spots such as next and execute much faster, so I think it's worth it. 2020-07-07 13:31:00 +10:00			`CODE _crc16 ( c n -- c ) EXX, ( protect BC )`
z80a: make mnemonic names more uniform across assemblers Initially, I used the same letters as those used in the z80 ref docs, but it makes the different assemblers harder to use than they should. Having consistent "argtype" rules across assemblers should help. 2020-06-28 12:01:56 +10:00			`HL POP, ( n ) DE POP, ( c )`
sdc: implement _crc16 in z80 2020-04-25 10:46:01 +10:00			`A L LDrr, D XORr, D A LDrr,`
z80a: make mnemonic names more uniform across assemblers Initially, I used the same letters as those used in the z80 ref docs, but it makes the different assemblers harder to use than they should. Having consistent "argtype" rules across assemblers should help. 2020-06-28 12:01:56 +10:00			`B 8 LDri,`
sdc: implement _crc16 in z80 2020-04-25 10:46:01 +10:00			`BEGIN,`
z80a: make mnemonic names more uniform across assemblers Initially, I used the same letters as those used in the z80 ref docs, but it makes the different assemblers harder to use than they should. Having consistent "argtype" rules across assemblers should help. 2020-06-28 12:01:56 +10:00			`E SLA, D RL,`
sdc: implement _crc16 in z80 2020-04-25 10:46:01 +10:00			`IFC, ( msb is set, apply polynomial )`
z80a: make mnemonic names more uniform across assemblers Initially, I used the same letters as those used in the z80 ref docs, but it makes the different assemblers harder to use than they should. Having consistent "argtype" rules across assemblers should help. 2020-06-28 12:01:56 +10:00			`A D LDrr, 0x10 XORi, D A LDrr,`
			`A E LDrr, 0x21 XORi, E A LDrr,`
sdc: implement _crc16 in z80 2020-04-25 10:46:01 +10:00			`THEN,`
			`DJNZ, AGAIN,`
z80a: make mnemonic names more uniform across assemblers Initially, I used the same letters as those used in the z80 ref docs, but it makes the different assemblers harder to use than they should. Having consistent "argtype" rules across assemblers should help. 2020-06-28 12:01:56 +10:00			`DE PUSH,`
z80: Use BC as IP register instead of IY It's a bit more inconvenient in terms of register protection (BC is much more generally useful than IY), but it makes tight spots such as next and execute much faster, so I think it's worth it. 2020-07-07 13:31:00 +10:00			`EXX, ( unprotect BC ) ;CODE`