# Z80 assembler specificities

Load with "Z80A".

Mnemonics having only a single form, such as PUSH and POP,
don't have argtype suffixes.

Be aware that "SP" and "AF" refer to the same value: some 16-
bit ops can affect SP, others, AF. If you use the wrong argu-
ment on the wrong op, you will affect the wrong register.

# Flow examples

IFZ, NOP, ELSE, NOP, THEN,
BEGIN, NOP, JR, AGAIN, ( unconditional )
BEGIN, NOP, JRZ, AGAIN, ( conditional )
LSET L1 NOP, L1 BR JRi, ( backward jump )
FJR JRi, TO L1 NOP, L1 FMARK ( forward jump )

# IX+, IY+

IX/IY instructions are a bit complicated.  As a general rule,
IX and IY are equivalent to spitting an extra $dd / $fd and
then spit the equivalent of HL or (HL).

In "HL" op types, IX and IY words can be used simply. Examples:

IX PUSH,
IY POP,
IX $1234 LDdi,
HL ADDIXd,

In "(HL)" op types, all IX/IY words contain displacements and
need to be used with IX+ and IY+ prefix words.

Examples:

0 IX+ E LDIXY, ( ld e, (ix+0) )
-2 IY+ INC(IXY+), ( inc (iy-2) )

# Instructions list

Letters in [] brackets indicate "argtype" variants. When the
bracket starts with ",", it means that a "plain" mnemonic is
available. For example, "RET," and "RETc," exist.

r => A B C D E H L (HL)
d => BC DE HL AF/SP
c => CNZ CZ CNC CC CPO CPE CP CM
i => immediate
(i) => memory reference (both 8b and 16b)

LD  [rr, ri, di, (i)HL, HL(i), d(i), (i)d, rIXY, IXYr,
    (DE)A, A(DE), (i)A, A(i)]
ADD [r, i, HLd, IXd, IXIX, IYd, IYIY]
ADC [r, HLd]
CP  [r, i, (IXY+)]
SBC [r, HLd]
SUB [r, i]
INC [r, d, (IXY+)]
DEC [r, d, (IXY+)]
AND [r, i]
OR  [r, i]
XOR [r, i]
OUT [iA, (C)r]
IN  [Ai, r(C)]
JP  [, c, (HL), (IX), (IY)]
JR  [, Z, NZ, C, NC]
CALL[, c]
RET [, c]

PUSH       POP
SET        RES         BIT
RL         RLC         SLA         RLA         RLCA
RR         RRC         SRL         RRA         RRCA
RST        DJNZ
DI         EI          EXDEHL      EXX         HALT
NOP        RETI        RETN        SCF
CPI        CPIR        CPD         CPDR        IM0
IM1        IM2         INI         LDI         LDIR
LDD        LDDR        NEG         OUTI

Macros:

SUBHLd     Clear carry + SBCHLd
PUSHA      Push value of A. Destroys BC
HLZ        Set Z according to HL. Destroys A
DEZ        Set Z according to DE. Destroys A
BCZ        Set Z according to BC. Destroys A
LDDE(HL)   16-bit LD from (HL) to DE. HL+1
LDBC(HL)   16-bit LD from (HL) to BC. HL+1
LDHL(HL)   16-bit LD from (HL) to HL. Destroys A
OUTHL      ( port -- ) OUT H, then OUT L. Destroys A
OUTDE      ( port -- ) OUT D, then OUT E. Destroys A