Trevor Merritt
e29ac45c84
scroll left and right work in stdef and hidef adds octo test roms adds schip fonts to memory
36 lines
1.1 KiB
Plaintext
36 lines
1.1 KiB
Plaintext
###########################################
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#
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# MacroMirror
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#
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# Statically compute vertically or
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# horizontally mirrored copies of 8x8 sprites
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# using macros and the '@' operator.
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# These techniques generalize readily to
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# arbitrary-sized memory blocks.
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#
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# John Earnest
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#
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###########################################
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: main
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v1 := 10
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i := sprite-1 sprite v0 v0 8
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i := sprite-2 sprite v0 v1 8
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i := sprite-3 sprite v1 v0 8
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i := sprite-4 sprite v1 v1 8
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loop again
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# see http://graphics.stanford.edu/~seander/bithacks.html#ReverseByteWith32Bits
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:macro rev8 X { :byte { 0xFF & ( 0x10101 * ( 0x22110 & 0x0802 * X ) | 0x88440 & 0x8020 * X ) >> 16 } }
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:macro mirror-v_ { :byte { @ from + 7 - HERE - to } }
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:macro mirror-h_ { :calc t { @ from + HERE - to } rev8 t }
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:macro mirror-8 BASE OP { :calc to { HERE } :calc from { BASE } OP OP OP OP OP OP OP OP }
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:macro mirror-v BASE { mirror-8 BASE mirror-v_ }
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:macro mirror-h BASE { mirror-8 BASE mirror-h_ }
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: sprite-1 0x18 0x2C 0x46 0x83 0xEF 0x2C 0x2C 0x3C
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: sprite-3 0x18 0x14 0xF2 0x81 0xF3 0xF6 0x1C 0x18
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: sprite-2 mirror-v sprite-1
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: sprite-4 mirror-h sprite-3
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