mirror of
https://github.com/lscharen/iigs-game-engine.git
synced 2024-11-28 04:50:07 +00:00
398 lines
13 KiB
ArmAsm
398 lines
13 KiB
ArmAsm
****************************************
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* Basic Error Macro *
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****************************************
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_Err mac
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bcc NoErr
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do ]0 ; (DO if true)
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jsr PgmDeath ; this is conditionally compiled if
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str ]1 ; we pass in an error statement
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else ; (ELSE)
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jmp PgmDeath0 ; we just call the simpler error handler
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fin ; (FIN)
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NoErr eom
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;
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; Dereference a handle that is on the top of the stack
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;
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_Deref MAC
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phb ; save caller's data bank register
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pha ; push high word of handle on stack
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plb ; sets B to the bank byte of the pointer
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lda |$0002,x ; load the high word of the master pointer
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pha ; and save it on the stack
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lda |$0000,x ; load the low word of the master pointer
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tax ; and return it in X
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pla ; restore the high word in A
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plb ; pull the handle's high word high byte off the
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; stack
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plb ; restore the caller's data bank register
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<<<
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; Call _NewHandle, but track the allocation
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_TrackHandle mac
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_NewHandle
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bcs err
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ldx NumHandles
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lda 1,s
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sta Handles,x
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lda 3,s
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sta Handles+2,x
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txa
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adc #4
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sta NumHandles
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err
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<<<
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_Mul128 mac
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asl
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asl
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asl
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asl
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asl
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asl
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asl
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<<<
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; Possible optimization (assumes accumulator is <512). 8 cycles/5 bytes vs 14 cycles/7 bytes
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; cmp #$0100
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; xba
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; ror
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_Div16 mac
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lsr
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lsr
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lsr
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lsr
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<<<
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_R0W0 mac ; Read Bank 0 / Write Bank 0
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ldal STATE_REG
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and #$FFCF
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stal STATE_REG
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<<<
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_R0W1 mac ; Read Bank 0 / Write Bank 1
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ldal STATE_REG
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ora #$0010
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stal STATE_REG
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<<<
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_R1W1 mac ; Read Bank 0 / Write Bank 1
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ldal STATE_REG
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ora #$0030
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stal STATE_REG
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<<<
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_PushReg mac ; Used to save/restore registers when calling subroutines.
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pha
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phx
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phy
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<<<
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_PullReg mac
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ply
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plx
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pla
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<<<
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_PushReg2 mac ; Variation to also save the P-register to preserve m/x
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pha
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phx
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phy
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php
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<<<
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_PullReg2 mac
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plp
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ply
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plx
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pla
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<<<
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jne mac
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beq *+5
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jmp ]1
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<<<
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jeq mac
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bne *+5
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jmp ]1
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<<<
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jcc mac
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bcs *+5
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jmp ]1
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<<<
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jcs mac
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bcc *+5
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jmp ]1
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<<<
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min mac
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cmp ]1
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bcc mout
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lda ]1
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mout <<<
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; Increment a value mod some number.
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incmod mac
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inc
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cmp ]1
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bcc out
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lda #0
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out <<<
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decmod mac
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dec
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bpl out
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lda ]1
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dec
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out <<<
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adcmod mac
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adc ]1
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cmp ]2
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bcc out
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sbc ]2
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out <<<
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sbcmod mac
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sbc ]1
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bpl out
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clc
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adc ]2
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out <<<
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asr16 mac
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cmp #$8000
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ror
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<<<
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asr8 mac
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cmp #$80
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ror
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<<<
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; Macro to define script steps
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ScriptStep MAC
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IF #=]5
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dw {]1+{{]5&#$000F}<<8}},]2,]3,]4
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ELSE
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dw ]1,]2,]3,]4
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FIN
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<<<
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; A specialized CopyMaskedWord macro that draws a tile from a direct page workspace. Used
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; to render fringe tiles and sprite tiles when BG1 is active. If there is no second background,
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; then one should use the optimized functions which assumes a PEA opcode and only
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; needs to copy data words
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;
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; ]1 : tiledata direct page address , the tilemask direct page address is tiledata + 32
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; ]2 : code field offset
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CopyMaskedWordD MAC
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lda ]1+32 ; load the mask value
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bne mixed ; a non-zero value may be mixed
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; This is a solid word
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lda #$00F4 ; PEA instruction
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sta: ]2,y
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lda ]1 ; load the tile data
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sta: ]2+1,y ; PEA operand
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bra next
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mixed cmp #$FFFF ; All 1's in the mask is fully transparent
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beq transparent
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; This is the slowest path because there is a *lot* of work to do. So much that it's
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; worth it to change up the environment to optimize things a bit more.
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;
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; Need to fill in the first 10 bytes of the JMP handler with the following code sequence
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;
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; lda (00),y
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; and #MASK
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; ora #DATA
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lda #$004C ; JMP instruction
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sta: ]2,y
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ldx _X_REG ; Get the addressing offset
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ldal JTableOffset,x ; Get the address offset and add to the base address
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adc _BASE_ADDR ; of the current code field line
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adc #{]2&$F000} ; adjust for the current row offset
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sta: ]2+1,y
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tay ; This becomes the new address that we use to patch in
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txa ; Get the offset and render a LDA (dp),y instruction
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sep #$20
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sta: $0001,y ; LDA (00),y operand
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lda #$B1
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sta: $0000,y ; LDA (00),y opcode
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lda #$29
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sta: $0002,y ; AND #$0000 opcode
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lda #$09
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sta: $0005,y ; ORA #$0000 opcode
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rep #$20
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lda ]1+32 ; insert the tile mask and data into the exception
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sta: $0003,y ; handler.
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lda ]1
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sta: $0006,y
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lda #$0D80 ; branch to the prologue (BRA *+15)
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sta: $0008,y
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ldy _Y_REG ; restore original y-register value and move on
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bra next
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; This is a transparent word, so just show the second background layer
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transparent
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lda #$00B1 ; LDA (dp),y instruction
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sta: ]2,y
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lda _X_REG ; X is the logical tile offset (0, 2, 4, ... 82) left-to-right
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ora #$4800 ; put a PHA after the offset
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sta: ]2+1,y
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next
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eom
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; Macros to use in the Masked Tile renderer
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;
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; ]1 : tiledata offset
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; ]2 : tilemask offset
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; ]3 : code field offset
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CopyMaskedWord MAC
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ldal ]2,x ; load the mask value
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bne mixed ; a non-zero value may be mixed
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; This is a solid word
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lda #$00F4 ; PEA instruction
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sta: ]3,y
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ldal ]1,x ; load the tile data
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sta: ]3+1,y ; PEA operand
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bra next
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mixed cmp #$FFFF ; All 1's in the mask is fully transparent
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beq transparent
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; This is the slowest path because there is a *lot* of work to do. So much that it's
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; worth it to change up the environment to optimize things a bit more.
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;
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; Need to fill in the first 8 bytes of the JMP handler with the following code sequence
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;
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; lda (00),y
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; and #MASK
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; ora #DATA
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lda #$004C ; JMP instruction
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sta: ]3,y
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ldx _X_REG ; Get the addressing offset
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ldal JTableOffset,x ; Get the address offset and add to the base address
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ora _BASE_ADDR ; of the current code field row (2 rows per bank) $0000 or $8000
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ora #{]3&$7000} ; adjust for the current line offset within the row
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sta: ]3+1,y
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tay ; This becomes the new address that we use to patch in
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txa ; Get the offset and render a LDA (dp),y instruction
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sep #$20
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sta: $0001,y ; LDA (00),y operand
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lda #$B1
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sta: $0000,y ; LDA (00),y opcode
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lda #$29
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sta: $0002,y ; AND #$0000 opcode
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lda #$09
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sta: $0005,y ; ORA #$0000 opcode
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rep #$20
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ldx _T_PTR ; restore the original x-register value
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ldal ]2,x ; insert the tile mask and data into the exception
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sta: $0003,y ; handler.
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ldal ]1,x
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sta: $0006,y
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; Copy the top 9 bytes down. We have 23 bytes of space and are only using 8. Since 9 + 8 = 17 < 23, we
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; can save 3 cycles per word by eliminating the BRA instruction
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; lda #$0D80 ; branch to the prologue (BRA *+15)
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; sta: $0008,y
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lda: $0017,y
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sta: $0008,y
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lda: $0019,y
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sta: $000A,y
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lda: $001B,y
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sta: $000C,y
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lda: $001D,y
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sta: $000E,y
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lda: $001E,y
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sta: $000F,y
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ldy _Y_REG ; restore original y-register value and move on
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bra next
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; This is a transparent word, so just show the second background layer
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transparent
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lda #$00B1 ; LDA (dp),y instruction
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sta: ]3,y
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lda _X_REG ; X is the logical tile offset (0, 2, 4, ... 82) left-to-right
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ora #$4800 ; put a PHA after the offset
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sta: ]3+1,y
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next
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eom
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; Large code blocks that can be used in sprite blitters
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; ]1: line number
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OneSpriteToCodeField mac
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lda blttmp+{]1*4}
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andl spritemask+{]1*SPRITE_PLANE_SPAN},x
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oral spritedata+{]1*SPRITE_PLANE_SPAN},x
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sta: $0004+{]1*$1000},y
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lda blttmp+{]1*4}+2
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andl spritemask+{]1*SPRITE_PLANE_SPAN}+2,x
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oral spritedata+{]1*SPRITE_PLANE_SPAN}+2,x
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sta: $0001+{]1*$1000},y
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eom
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TwoSpritesToCodeField mac
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ldy #{]1*SPRITE_PLANE_SPAN}
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lda blttmp+{]1*4}
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andl [spritemask_1],y
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oral [spritedata_1],y
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andl [spritemask_0],y
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oral [spritedata_0],y
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sta: $0004+{]1*$1000},x
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ldy #{]1*SPRITE_PLANE_SPAN}+2
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lda blttmp+{]1*4}+2
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andl [spritemask_1],y
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oral [spritedata_1],y
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andl [spritemask_0],y
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oral [spritedata_0],y
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sta: $0001+{]1*$1000},x
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eom
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ThreeSpritesToCodeField mac
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ldy #{]1*SPRITE_PLANE_SPAN}
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lda blttmp+{]1*4}
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andl [spritemask_2],y
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oral [spritedata_2],y
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andl [spritemask_1],y
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oral [spritedata_1],y
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andl [spritemask_0],y
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oral [spritedata_0],y
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sta: $0004+{]1*$1000},x
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ldy #{]1*SPRITE_PLANE_SPAN}+2
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lda blttmp+{]1*4}+2
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andl [spritemask_2],y
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oral [spritedata_2],y
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andl [spritemask_1],y
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oral [spritedata_1],y
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andl [spritemask_0],y
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oral [spritedata_0],y
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sta: $0001+{]1*$1000},x
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eom
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