iigs-game-engine/macros/CORE.MACS.S
2022-02-18 20:43:55 -06:00

328 lines
11 KiB
ArmAsm

****************************************
* 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
;
; 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 <<<
; Increment a value mod some number.
incmod mac
inc
cmp ]1
bcc out
lda #0
out <<<
decmod mac
dec
bpl out
lda ]1
dec
out <<<
adcmod mac
adc ]1
cmp ]2
bcc out
sbc ]2
out <<<
sbcmod mac
sbc ]1
bpl out
clc
adc ]2
out <<<
asr16 mac
cmp #$8000
ror
<<<
asr8 mac
cmp #$80
ror
<<<
; Macro to define script steps
ScriptStep MAC
IF #=]5
dw {]1+{{]5&#$000F}<<8}},]2,]3,]4
ELSE
dw ]1,]2,]3,]4
FIN
<<<
; A specialized CopyMaskedWord macro that draws a tile from a direct page workspace. Used
; to render fringe tiles and sprite tiles when BG1 is active. If there is no second background,
; then one should use the optimized functions which assumes a PEA opcode and only
; needs to copy data words
;
; ]1 : tiledata direct page address , the tilemask direct page address is tiledata + 32
; ]2 : code field offset
CopyMaskedWordD MAC
lda ]1+32 ; load the mask value
bne mixed ; a non-zero value may be mixed
; This is a solid word
lda #$00F4 ; PEA instruction
sta: ]2,y
lda ]1 ; load the tile data
sta: ]2+1,y ; PEA operand
bra next
mixed cmp #$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.
;
; Need to fill in the first 10 bytes of the JMP handler with the following code sequence
;
; lda (00),y
; and #MASK
; ora #DATA
lda #$004C ; JMP instruction
sta: ]2,y
ldx _X_REG ; Get the addressing offset
ldal JTableOffset,x ; Get the address offset and add to the base address
adc _BASE_ADDR ; of the current code field line
adc #{]2&$F000} ; adjust for the current row offset
sta: ]2+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
sep #$20
sta: $0001,y ; LDA (00),y operand
lda #$B1
sta: $0000,y ; LDA (00),y opcode
lda #$29
sta: $0002,y ; AND #$0000 opcode
lda #$09
sta: $0005,y ; ORA #$0000 opcode
rep #$20
lda ]1+32 ; insert the tile mask and data into the exception
sta: $0003,y ; handler.
lda ]1
sta: $0006,y
lda #$0D80 ; branch to the prologue (BRA *+15)
sta: $0008,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: ]2,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: ]2+1,y
next
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.
;
; Need to fill in the first 8 bytes of the JMP handler with the following code sequence
;
; lda (00),y
; and #MASK
; ora #DATA
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
ora _BASE_ADDR ; of the current code field row (2 rows per bank) $0000 or $8000
ora #{]3&$7000} ; adjust for the current line offset within the row
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
sep #$20
sta: $0001,y ; LDA (00),y operand
lda #$B1
sta: $0000,y ; LDA (00),y opcode
lda #$29
sta: $0002,y ; AND #$0000 opcode
lda #$09
sta: $0005,y ; ORA #$0000 opcode
rep #$20
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
; Copy the top 9 bytes down. We have 23 bytes of space and are only using 8. Since 9 + 8 = 17 < 23, we
; can save 3 cycles per word by eliminating the BRA instruction
; lda #$0D80 ; branch to the prologue (BRA *+15)
; sta: $0008,y
lda: $0017,y
sta: $0008,y
lda: $0019,y
sta: $000A,y
lda: $001B,y
sta: $000C,y
lda: $001D,y
sta: $000E,y
lda: $001E,y
sta: $000F,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