megadrive_test1

annotate src/vdp.c @ 6:862f8a034cae

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expanding the megadrive code
author John Tsiombikas <nuclear@member.fsf.org>
date Sat, 11 Feb 2017 08:56:42 +0200
parents
children 8253942b0a1a
rev   line source
nuclear@6 1 #include <stdint.h>
nuclear@6 2 #include "vdp.h"
nuclear@6 3 #include "io.h"
nuclear@6 4 #include "misc.h"
nuclear@6 5
nuclear@6 6 static void *tilemap_ptr[3];
nuclear@6 7
nuclear@6 8 int vdp_init(void)
nuclear@6 9 {
nuclear@6 10 unsigned int mode1_flags = VDP_REG1_DISP_BIT;
nuclear@6 11
nuclear@6 12 if(mdg_ispal()) {
nuclear@6 13 mode1_flags |= VDP_REG1_30CELL_BIT;
nuclear@6 14 }
nuclear@6 15
nuclear@6 16 VDP_SET_REG(0, VDP_REG0_BASE);
nuclear@6 17 VDP_SET_REG(1, VDP_REG1_BASE | mode1_flags);
nuclear@6 18
nuclear@6 19 return 0;
nuclear@6 20 }
nuclear@6 21
nuclear@6 22 void vdp_set_tilemap_slot(int plane, int slot)
nuclear@6 23 {
nuclear@6 24 switch(plane) {
nuclear@6 25 case VDP_PLANE_A:
nuclear@6 26 VDP_SET_REG(VDP_REG_PADDR_A, (slot & 7) << 3);
nuclear@6 27 tilemap_ptr[VDP_PLANE_A] = (void*)((uint32_t)slot << 13);
nuclear@6 28 break;
nuclear@6 29
nuclear@6 30 case VDP_PLANE_WIN:
nuclear@6 31 VDP_SET_REG(VDP_REG_PADDR_WIN, (slot & 0x1f) << 1);
nuclear@6 32 tilemap_ptr[VDP_PLANE_WIN] = (void*)((uint32_t)slot << 11);
nuclear@6 33 break;
nuclear@6 34
nuclear@6 35 case VDP_PLANE_B:
nuclear@6 36 VDP_SET_REG(VDP_REG_PADDR_B, slot & 7);
nuclear@6 37 tilemap_ptr[VDP_PLANE_B] = (void*)((uint32_t)slot << 13);
nuclear@6 38 break;
nuclear@6 39 }
nuclear@6 40 }
nuclear@6 41
nuclear@6 42 void *vdp_tilemap_ptr(int plane)
nuclear@6 43 {
nuclear@6 44 return tilemap_ptr[plane];
nuclear@6 45 }
nuclear@6 46
nuclear@6 47 void vdp_setpal_rgb24(int idx, int r, int g, int b)
nuclear@6 48 {
nuclear@6 49 VDP_SET_CRAM_ADDR(idx);
nuclear@6 50 VDP_SET_CRAM_RGB24(r, g, b);
nuclear@6 51 }
nuclear@6 52
nuclear@6 53 void vdp_setpal(int idx0, int count, unsigned char *pal)
nuclear@6 54 {
nuclear@6 55 int i;
nuclear@6 56
nuclear@6 57 VDP_SET_CRAM_ADDR(idx0);
nuclear@6 58 for(i=0; i<count; i++) {
nuclear@6 59 VDP_SET_CRAM_RGB24(pal[0], pal[1], pal[2]);
nuclear@6 60 pal += 3;
nuclear@6 61 }
nuclear@6 62 }
nuclear@6 63
nuclear@6 64 #define SCROLLSIZE(x) \
nuclear@6 65 do { \
nuclear@6 66 switch(xtiles) { \
nuclear@6 67 case 32: \
nuclear@6 68 case 64: \
nuclear@6 69 (x) >>= 6; \
nuclear@6 70 break; \
nuclear@6 71 case 128: \
nuclear@6 72 (x) = 3; \
nuclear@6 73 break; \
nuclear@6 74 default: \
nuclear@6 75 panic("invalid argument to %s: %d\n", (x), __func__); \
nuclear@6 76 } \
nuclear@6 77 } while(0)
nuclear@6 78
nuclear@6 79 void vdp_set_scroll_size(int xtiles, int ytiles)
nuclear@6 80 {
nuclear@6 81 SCROLLSIZE(xtiles);
nuclear@6 82 SCROLLSIZE(ytiles);
nuclear@6 83
nuclear@6 84 VDP_SET_REG(VDP_REG_SCROLL_SIZE, (ytiles << 4) | xtiles);
nuclear@6 85 }