forked from Lephenixnoir/gint
29 lines
764 B
C
29 lines
764 B
C
#include <display/fx.h>
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/* masks() - compute the vram masks for a given rectangle */
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void masks(int x1, int x2, uint32_t *masks)
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{
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if(x1 < 0) x1 = 0;
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if(x2 < 0) x2 = 0;
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/* Indexes of the first and last non-empty longs */
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size_t l1 = x1 >> 5;
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size_t l2 = x2 >> 5;
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size_t i = 0;
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/* Base masks (0's are final, 0xffffffff will be adjusted later) */
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while(i < l1) masks[i++] = 0x00000000;
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while(i <= l2) masks[i++] = 0xffffffff;
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while(i < 4) masks[i++] = 0x00000000;
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/* Remove the index information in x1 and x2 (it's now in l1 and l2)
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and keep only the offsets */
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x1 &= 31;
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/* For x2 we also want the complement to 31 to invert the shift */
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x2 = ~x2 & 31;
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/* Now roll! */
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masks[l1] &= (0xffffffffu >> x1);
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masks[l2] &= (0xffffffffu << x2);
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}
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