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40 lines
978 B
C
40 lines
978 B
C
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/* SPDX-License-Identifier: GPL-2.0-only
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*
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* Virtual memory framebuffer access for drawing routines
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*
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* Copyright (C) 2025 Zsolt Kajtar (soci@c64.rulez.org)
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*/
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/* keeps track of a bit address in framebuffer memory */
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struct fb_address {
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void *address;
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int bits;
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};
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/* initialize the bit address pointer to the beginning of the frame buffer */
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static inline struct fb_address fb_address_init(struct fb_info *p)
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{
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void *base = p->screen_buffer;
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struct fb_address ptr;
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ptr.address = PTR_ALIGN_DOWN(base, BITS_PER_LONG / BITS_PER_BYTE);
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ptr.bits = (base - ptr.address) * BITS_PER_BYTE;
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return ptr;
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}
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/* framebuffer write access */
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static inline void fb_write_offset(unsigned long val, int offset, const struct fb_address *dst)
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{
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unsigned long *mem = dst->address;
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mem[offset] = val;
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}
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/* framebuffer read access */
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static inline unsigned long fb_read_offset(int offset, const struct fb_address *src)
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{
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unsigned long *mem = src->address;
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return mem[offset];
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}
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