forked from Lephenixnoir/gint
56 lines
1.1 KiB
C
56 lines
1.1 KiB
C
#include <screen.h>
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#include <stdint.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 operations.
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*/
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void screen_display(const void *ptr)
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{
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volatile uint8_t *selector = (void *)0xb4000000;
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volatile uint8_t *data = (void *)0xb4010000;
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const uint8_t *vram = ptr;
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for(int 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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// We could loop but I suspect it will be faster to iterate.
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*selector = 7;
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/* TODO Manually load the video-ram line into the cache? */
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*data = *vram++;
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*data = *vram++;
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*data = *vram++;
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*data = *vram++;
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*data = *vram++;
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*data = *vram++;
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*data = *vram++;
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*data = *vram++;
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*data = *vram++;
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*data = *vram++;
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*data = *vram++;
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*data = *vram++;
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*data = *vram++;
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*data = *vram++;
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*data = *vram++;
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*data = *vram++;
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}
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}
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