forked from Lephenixnoir/gint
52 lines
1.2 KiB
C
52 lines
1.2 KiB
C
/*
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screen.c
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This module is in charge of interaction with the physical screen. See
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module 'display' for video ram management and drawing.
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The screen basically has two input values, which are a register
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selector and the selected register's value. What this module does is
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essentially selecting registers by setting *selector and assigning them
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values by setting *data.
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*/
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#include <screen.h>
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/*
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screen_display()
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Displays the given vram on the screen. Only bytes can be transferred
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through the screen registers, which is unfortunate because most of the
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vram-related operations use longword-base computations.
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@arg vram 1024-byte video buffer.
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*/
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void screen_display(const void *ptr)
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{
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const char *vram = (const char *)ptr;
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volatile char *selector = (char *)0xb4000000;
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volatile char *data = (char *)0xb4010000;
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int line, bytes;
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for(line = 0; line < 64; line++)
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{
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// Setting the x-address register.
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*selector = 4;
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*data = line + 0xc0;
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// Setting Y-Up mode.
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*selector = 1;
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*data = 1;
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// Setting y-address.
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*selector = 4;
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*data = 0;
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// Selecting data write register 7 and sending a line's bytes.
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*selector = 7;
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for(bytes = 0; bytes < 16; bytes++) *data = *vram++;
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}
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}
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