iigs-game-engine/macros/APP.MACS.S

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ArmAsm
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2020-08-23 05:25:39 +00:00
;
; Dereference a handle that is on the top of the stack
;
_Deref MAC
phb ; save caller's data bank register
pha ; push high word of handle on stack
plb ; sets B to the bank byte of the pointer
lda |$0002,x ; load the high word of the master pointer
pha ; and save it on the stack
lda |$0000,x ; load the low word of the master pointer
tax ; and return it in X
pla ; restore the high word in A
plb ; pull the handle's high word high byte off the
; stack
plb ; restore the caller's data bank register
<<<
_Mul128 mac
asl
asl
asl
asl
asl
asl
asl
<<<
; Possible optimization (assumes accumulator is <512). 8 cycles/5 bytes vs 14 cycles/7 bytes
; cmp #$0100
; xba
; ror
_Div16 mac
lsr
lsr
lsr
lsr
<<<
_R0W0 mac ; Read Bank 0 / Write Bank 0
ldal STATE_REG
and #$FFCF
stal STATE_REG
<<<
_R0W1 mac ; Read Bank 0 / Write Bank 1
ldal STATE_REG
ora #$0010
stal STATE_REG
<<<
_R1W1 mac ; Read Bank 0 / Write Bank 1
ldal STATE_REG
ora #$0030
stal STATE_REG
<<<
_PushReg mac ; Used to save/restore registers when calling subroutines.
pha
phx
phy
<<<
_PullReg mac
ply
plx
pla
<<<
_PushReg2 mac ; Variation to also save the P-register to preserve m/x
pha
phx
phy
php
<<<
_PullReg2 mac
plp
ply
plx
pla
<<<
jne mac
beq *+5
jmp ]1
<<<
jeq mac
bne *+5
jmp ]1
<<<
jcc mac
bcs *+5
jmp ]1
<<<
jcs mac
bcc *+5
jmp ]1
<<<
min mac
cmp ]1
bcc mout
lda ]1
mout <<<
2020-08-23 05:25:39 +00:00
****************************************
* Basic Error Macro *
****************************************
_Err mac
bcc NoErr
do ]0 ; (DO if true)
jsr PgmDeath ; this is conditionally compiled if
str ]1 ; we pass in an error statement
else ; (ELSE)
jmp PgmDeath0 ; we just call the simpler error handler
fin ; (FIN)
NoErr eom
; Macros to use in the Masked Tile renderer
;
; ]1 : tiledata offset
; ]2 : tilemask offset
; ]3 : code field offset
CopyMaskedWord MAC
ldal ]2,x ; load the mask value
bne mixed ; a non-zero value may be mixed
; This is a solid word
lda #$00F4 ; PEA instruction
sta: ]3,y
ldal ]1,x ; load the tile data
sta: ]3+1,y ; PEA operand
bra next
mixed cmp #$FFFF ; All 1's in the mask is fully transparent
beq transparent
; This is the slowest path because there is a *lot* of work to do. So much that it's
; worth it to change up the environment to optimize things a bit more.
lda #$004C ; JMP instruction
sta: ]3,y
ldx _X_REG ; Get the addressing offset
ldal JTableOffset,x ; Get the address offset and add to the base address
; clc ; may be able to be removed...
adc _BASE_ADDR ; of the current code field line
adc #{]3&$F000} ; adjust for the current row offset
sta: ]3+1,y
tay ; This becomes the new address that we use to patch in
txa ; Get the offset and render a LDA (dp),y instruction
xba
ora #$00B1
sta: $0000,y
ldx _T_PTR ; restore the original x-register value
ldal ]2,x ; insert the tile mask and data into the exception
sta: $0003,y ; handler.
ldal ]1,x
sta: $0006,y
ldy _Y_REG ; restore original y-register value and move on
bra next
; This is a transparent word, so just show the second background layer
transparent
lda #$00B1 ; LDA (dp),y instruction
sta: ]3,y
lda _X_REG ; X is the logical tile offset (0, 2, 4, ... 82) left-to-right
ora #$4800 ; put a PHA after the offset
sta: ]3+1,y
next
eom