2015-09-20 10:59:36 +02:00
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/*
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BIOS has a scroll function!
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Very convenient, otherwise that would be hard to implement.
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How it works:
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Before scroll:
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a
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b
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c
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d
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We then choose to act on the rectangle with corners
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(1, 1) and (2, 2)} given by cx and dx:
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a
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XX
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XX
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d
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and scroll that rectangle down by one line (al).
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The final outcome is:
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a
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c
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NN
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d
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where `N` are new squares generated by the scroll,
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which gets filled with the background color in bh.
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*/
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#include "common.h"
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BEGIN
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/* Print staircase. */
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CLEAR
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2015-09-20 15:51:38 +02:00
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PUTC($0x61)
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PUTC($0x0A)
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PUTC($0x62)
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PUTC($0x0A)
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PUTC($0x63)
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PUTC($0x0A)
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PUTC($0x64)
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2015-09-20 10:59:36 +02:00
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/* Function ID. */
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mov $0x06, %ah
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/* nr. of lines to scroll */
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mov $0x01, %al
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/*
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BIOS color attributes.
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Background is the clear color.
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Foreground is set as the new foreground color.
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*/
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mov $0xA4, %bh
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/*
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CH,CL: row,column upper left corner (00:00)
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TODO what does that mean?
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*/
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mov $0x0101, %cx
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/*
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DH,DL: row,column lower right corner (24:79).
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TODO what does it mean?
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*/
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mov $0x0202, %dx
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int $0x10
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hlt
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END
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