Routines
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76AB: Draw Actor Sprite Row
Does the same as DrawOldSpriteRow_Aligned, but for the sprite prepared by PrepareActorSprite.
Input
DE Address of the sprite data
HL Screen address
Output
DE Address of the next row of sprite data
HL Screen address of the row above
The entry point for a sprite which is aligned to a character cell.
DrawActorSpriteRow_Aligned 76AB EX DE,HL DE=the row of sprite data, and HL=the address of the next row.
76AC EX (SP),HL HL=the screen address, and the address of the next row of sprite data is stored on the stack.
76AD JR DrawSpriteRow_Write Jump to DrawSpriteRow_Write.
This entry point is used by the routine at XORSpriteLoop.
The entry point for a sprite which is not aligned to a character cell.
DrawActorSpriteRow 76AF PUSH HL Stash the screen address on the stack.
76B0 EX DE,HL HL=the address of the sprite data, and DE=the screen address.
76B1 PUSH DE Stash the screen address on the stack again.
76B2 LD D,(HL) D=the first byte of the row.
76B3 INC HL Move to the next byte of sprite data.
76B4 LD E,(HL) E=the second byte of the row.
76B5 INC HL Move on to the next row of sprite data.
76B6 EX DE,HL HL=the row of sprite data, and DE=the address of the next row.
76B7 XOR A A=00.
Self modifying code; the operand of this command is written by 7598. It jumps into the sequence of shifts below, so that the row is moved right by the right number of pixels.
DrawActorSpriteRow_Shift 76B8 JR DrawActorSpriteRow_Shift Jump to the first shift to do.
Shift the row left by up to seven bits; the bits which are shifted out of the row end up in A. The fourth shift is done with a longer command, but the jumps still land on the start of a shift.
76BA ADD HL,HL Shift HL left by one, moving the bit shifted out into A.
76BB ADC A,A
Shift the row left by up to seven bits; the bits which are shifted out of the row end up in A. The fourth shift is done with a longer command, but the jumps still land on the start of a shift.
76BC ADD HL,HL Shift HL left by one, moving the bit shifted out into A.
76BD ADC A,A
Shift the row left by up to seven bits; the bits which are shifted out of the row end up in A. The fourth shift is done with a longer command, but the jumps still land on the start of a shift.
76BE ADD HL,HL Shift HL left by one, moving the bit shifted out into A.
76BF ADC A,A
76C0 ADC HL,HL Shift HL left by one, moving the bit shifted out into A.
76C2 ADC A,A
76C3 ADD HL,HL Shift HL left by one, moving the bit shifted out into A.
76C4 ADC A,A
76C5 ADD HL,HL Shift HL left by one, moving the bit shifted out into A.
76C6 ADC A,A
76C7 ADD HL,HL Shift HL left by one, moving the bit shifted out into A.
76C8 ADC A,A
76C9 EX DE,HL DE=the shifted row, and HL=the address of the next row of sprite data.
76CA EX (SP),HL HL=the screen address, and the address of the next row of sprite data is stored on the stack.
76CB XOR (HL) Exclusive OR the first byte (in A) onto the screen.
76CC LD (HL),A Write the result to the screen.
76CD INC L Move to the next byte on the screen.
76CE JR DrawSpriteRow_Write Jump to DrawSpriteRow_Write.
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