48 lines
1.5 KiB
C
48 lines
1.5 KiB
C
#include <display.h>
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/* Add-in monochrome vram in gint's uninitialized bss section */
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__attribute__((section(".gint.bss"))) static uint32_t vram_local[256];
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__attribute__((section(".gint.bss"))) uint32_t *vram;
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/*
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display_getLocalVRAM()
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Returns gint's local video RAM address. Gint does not use the system's
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buffer because it is misaligned. This function always returns the same
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address. Both the display and the gray module heavily use this buffer;
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make sure you don't interfere with them if you access it.
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This function does not necessarily returns the video ram that is
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currently in use; call display_getCurrentVRAM() for this.
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*/
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inline uint32_t *display_getLocalVRAM(void)
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{
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return vram_local;
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}
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/*
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display_getCurrentVRAM()
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Returns the current monochrome video ram buffer. This function usually
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returns the parameter of the last call to display_useVRAM(), or the
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local vram address (which is default when the library starts).
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The return value of this function is undefined if the gray engine is
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running.
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*/
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inline uint32_t *display_getCurrentVRAM(void)
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{
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return vram;
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}
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/*
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display_useVRAM()
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Changes the current monochrome video ram address. The argument must be
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a 4-aligned 1024-byte buffer because the library's design requires it.
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This function refuses misaligned buffers but trusts that enough space
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is available; failing to provide enough memory may crash the program.
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This function will most likely have no effect when running the gray
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engine.
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*/
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inline void display_useVRAM(uint32_t *ptr)
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{
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if((uintptr_t)ptr & 3) return;
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vram = ptr;
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}
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