Routines
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38881: Draw New Entity Row
Used by the routine at XORSpriteLoop.
Draws one row of the new sprite, using XOR, and moves up to the next row. It is a copy of DrawOldEntityRow that uses the jump at DrawNewEntityRow_Jump, which is changed by PrepDraw2.
Input
B Page of the shift table
DE Pointer to the pixel data
HL Screen address of the row
C Number of rows left
Output
C Number of rows left
DE Pointer to the next row of pixel data
HL Screen address of the next row
DrawNewEntityRow 38881 LD A,C Copy the row count to A.
38882 EX AF,AF' Store the row count in AF'.
38883 LD A,(DE) Fetch the first byte of the row.
38884 LD C,A Copy it to C to use as the index into the shift table.
38885 PUSH HL Stash the screen address on the stack.
DrawNewEntityRow_Jump 38886 JR DrawNewEntityRow_Jump Jump into the unrolled code. The operand of this instruction is changed by PrepDraw2.
DrawNewEntityRow_Byte_1 38888 LD A,(DE) Byte 1 of the row: look up the shifted byte for the left cell and XOR it onto the screen.
38889 LD C,A
38890 LD A,(BC)
38891 XOR (HL)
38892 LD (HL),A
38893 INC L
DrawNewEntityRow_Byte_1_Right 38894 INC B Look up the shifted byte for the cell to the right and XOR it onto the screen, then move on to the next byte of pixel data.
38895 LD A,(BC)
38896 XOR (HL)
38897 LD (HL),A
38898 DEC B
38899 INC DE
DrawNewEntityRow_Byte_2 38900 LD A,(DE) Byte 2 of the row: look up the shifted byte for the left cell and XOR it onto the screen.
38901 LD C,A
38902 LD A,(BC)
38903 XOR (HL)
38904 LD (HL),A
38905 INC L
DrawNewEntityRow_Byte_2_Right 38906 INC B Look up the shifted byte for the cell to the right and XOR it onto the screen, then move on to the next byte of pixel data.
38907 LD A,(BC)
38908 XOR (HL)
38909 LD (HL),A
38910 DEC B
38911 INC DE
DrawNewEntityRow_Byte_3 38912 LD A,(DE) Byte 3 of the row: look up the shifted byte for the left cell and XOR it onto the screen.
38913 LD C,A
38914 LD A,(BC)
38915 XOR (HL)
38916 LD (HL),A
38917 INC L
DrawNewEntityRow_Byte_3_Right 38918 INC B Look up the shifted byte for the cell to the right and XOR it onto the screen, then move on to the next byte of pixel data.
38919 LD A,(BC)
38920 XOR (HL)
38921 LD (HL),A
38922 DEC B
38923 INC DE
DrawNewEntityRow_Byte_4 38924 LD A,(DE) Byte 4 of the row: look up the shifted byte for the left cell and XOR it onto the screen.
38925 LD C,A
38926 LD A,(BC)
38927 XOR (HL)
38928 LD (HL),A
38929 INC L
DrawNewEntityRow_Byte_4_Right 38930 INC B Look up the shifted byte for the cell to the right and XOR it onto the screen, then move on to the next byte of pixel data.
38931 LD A,(BC)
38932 XOR (HL)
38933 LD (HL),A
38934 DEC B
38935 INC DE
DrawNewEntityRow_Byte_5 38936 LD A,(DE) Byte 5 of the row: look up the shifted byte for the left cell and XOR it onto the screen.
38937 LD C,A
38938 LD A,(BC)
38939 XOR (HL)
38940 LD (HL),A
38941 INC L
DrawNewEntityRow_Byte_5_Right 38942 INC B Look up the shifted byte for the cell to the right and XOR it onto the screen, then move on to the next byte of pixel data.
38943 LD A,(BC)
38944 XOR (HL)
38945 LD (HL),A
38946 DEC B
38947 INC DE
DrawNewEntityRow_Byte_6 38948 LD A,(DE) Byte 6 of the row: look up the shifted byte for the left cell and XOR it onto the screen.
38949 LD C,A
38950 LD A,(BC)
38951 XOR (HL)
38952 LD (HL),A
38953 INC L
DrawNewEntityRow_Byte_6_Right 38954 INC B Look up the shifted byte for the cell to the right and XOR it onto the screen, then move on to the next byte of pixel data.
38955 LD A,(BC)
38956 XOR (HL)
38957 LD (HL),A
38958 DEC B
38959 INC DE
DrawNewEntityRow_Byte_7 38960 LD A,(DE) Byte 7 of the row: look up the shifted byte for the left cell and XOR it onto the screen.
38961 LD C,A
38962 LD A,(BC)
38963 XOR (HL)
38964 LD (HL),A
38965 INC L
DrawNewEntityRow_Byte_7_Right 38966 INC B Look up the shifted byte for the cell to the right and XOR it onto the screen, then move on to the next byte of pixel data.
38967 LD A,(BC)
38968 XOR (HL)
38969 LD (HL),A
38970 DEC B
38971 INC DE
DrawNewEntityRow_Byte_8 38972 LD A,(DE) Byte 8 of the row: look up the shifted byte for the left cell and XOR it onto the screen.
38973 LD C,A
38974 LD A,(BC)
38975 XOR (HL)
38976 LD (HL),A
38977 INC L
DrawNewEntityRow_Byte_8_Right 38978 INC B Look up the shifted byte for the cell to the right and XOR it onto the screen, then move on to the next byte of pixel data.
38979 LD A,(BC)
38980 XOR (HL)
38981 LD (HL),A
38982 DEC B
38983 INC DE
DrawNewEntityRow_Byte_9 38984 LD A,(DE) Byte 9 of the row: look up the shifted byte for the left cell and XOR it onto the screen.
38985 LD C,A
38986 LD A,(BC)
38987 XOR (HL)
38988 LD (HL),A
38989 INC L
DrawNewEntityRow_Byte_9_Right 38990 INC B Look up the shifted byte for the cell to the right and XOR it onto the screen, then move on to the next byte of pixel data.
38991 LD A,(BC)
38992 XOR (HL)
38993 LD (HL),A
38994 DEC B
38995 INC DE
DrawNewEntityRow_Byte_9_Next 38996 EX AF,AF' Fetch the row count from AF'.
38997 LD C,A Copy the row count to C.
38998 POP HL Restore the screen address from the stack.
38999 DEC H Move up one pixel line.
39000 LD A,H Fetch the inverse of the high byte of the address in A.
39001 CPL
39002 AND %00000111 Keep only the pixel line bits (bits 0-2).
39004 RET NZ Return if the move up stayed inside the same character cell.
39005 LD A,L Subtract 32 from the low byte to move up to the previous character row.
39006 SUB 32
39008 LD L,A
39009 RET C Return if the move up stayed inside the same third of the screen.
39010 LD A,H Add 8 to the high byte to move up to the previous third of the screen.
39011 ADD A,8
39013 LD H,A
39014 RET Return.
View the equivalent code in;
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