2020-12-30 03:14:26 +00:00
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# Test out the video mode by filling in the screen with pixels.
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#
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# To build a disk image:
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2021-03-15 04:41:47 +00:00
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# ./translate_subx boot.subx ex2.subx # emits disk.img
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2020-12-30 03:14:26 +00:00
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# To run:
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# qemu-system-i386 disk.img
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# Or:
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2021-03-16 04:59:08 +00:00
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# bochs -f bochsrc # bochsrc loads disk.img
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2020-12-30 03:14:26 +00:00
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2021-01-14 05:41:45 +00:00
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== code
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2021-03-16 03:39:23 +00:00
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Entry:
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2021-01-09 21:43:39 +00:00
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# ecx <- start of video memory
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2021-03-16 03:32:26 +00:00
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8b/-> *Video-memory-addr 1/r32/ecx
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2020-12-30 03:14:26 +00:00
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2021-01-09 21:43:39 +00:00
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# eax <- final pixel of video memory
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8d/copy-address *(ecx + 0x0bffff) 0/r32/eax # 0xbffff = 1024*768 - 1
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2020-12-30 03:14:26 +00:00
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2021-01-09 21:43:39 +00:00
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# for each pixel in video memory
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{
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39/compare %eax 1/r32/ecx
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7c/jump-if-< break/disp8
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# write its column number to it
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88/byte<- *eax 0/r32/AL
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48/decrement-eax
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eb/jump loop/disp8
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}
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2020-12-30 03:14:26 +00:00
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2021-01-09 21:43:39 +00:00
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# hang indefinitely
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{
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eb/jump loop/disp8
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}
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