50 lines
1.2 KiB
C
50 lines
1.2 KiB
C
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#include "neslib.h"
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#include "vrambuf.h"
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#include <string.h>
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// index to end of buffer
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byte updptr = 0;
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// add EOF marker to buffer (but don't increment pointer)
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void vrambuf_end(void) {
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VRAMBUF_SET(NT_UPD_EOF);
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}
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// clear vram buffer and place EOF marker
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void vrambuf_clear(void) {
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updptr = 0;
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vrambuf_end();
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}
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// wait for next frame, then clear buffer
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// this assumes the NMI will call flush_vram_update()
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void vrambuf_flush(void) {
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// make sure buffer has EOF marker
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vrambuf_end();
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// wait for next frame to flush update buffer
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// this will also set the scroll registers properly
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ppu_wait_frame();
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// clear the buffer
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vrambuf_clear();
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}
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// add multiple characters to update buffer
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// using horizontal increment
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void vrambuf_put(word addr, register const char* str, byte len) {
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// if bytes won't fit, wait for vsync and flush buffer
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if (VBUFSIZE-4-len < updptr) {
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vrambuf_flush();
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}
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// add vram address
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VRAMBUF_ADD((addr >> 8) ^ NT_UPD_HORZ);
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VRAMBUF_ADD(addr); // only lower 8 bits
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// add length
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VRAMBUF_ADD(len);
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// add data to buffer
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memcpy(updbuf+updptr, str, len);
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updptr += len;
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// place EOF mark
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vrambuf_end();
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}
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