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comparison src/vdp.c @ 19:04fc17376999

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Sort of working tile rendering and tile test ROM
author Michael Pavone <pavone@retrodev.com>
date Mon, 28 Mar 2016 23:43:31 -0700
parents 04d8efe7a1f0
children 91ded3b12d96
comparison
equal deleted inserted replaced
18:cc885122e9e3 19:04fc17376999
1 #include <stdint.h> 1 #include <stdint.h>
2 #include <string.h> 2 #include <string.h>
3 #include <stdio.h>
3 #include "vdp.h" 4 #include "vdp.h"
4 #include "system.h" 5 #include "system.h"
5 6
6 void vdp_init(vdp *context, uint32_t clock_div) 7 void vdp_init(vdp *context, uint32_t clock_div)
7 { 8 {
23 context->vcounter++; 24 context->vcounter++;
24 if (context->vcounter == 262) { 25 if (context->vcounter == 262) {
25 context->vcounter = 0; 26 context->vcounter = 0;
26 } 27 }
27 } 28 }
28 //TODO: do rendering stuff here 29 context->status &= ~(VDP_STATUS_VRAM|VDP_STATUS_SRAM);
30 //Render to linebuffer
31 if (context->vcounter > 15 && context->vcounter < 240 && context->hcounter < 406) {
32 if (context->hcounter < 246) {
33 context->status |= VDP_STATUS_VRAM;
34 if (!context->hcounter) {
35 //flip linebuffers
36 if (context->drawbuffer == context->linebuffers) {
37 context->drawbuffer = context->linebuffers + 328;
38 context->readbuffer = context->linebuffers;
39 } else {
40 context->drawbuffer = context->linebuffers;
41 context->readbuffer = context->linebuffers + 328;
42 }
43 context->draw_dest = 0;
44 }
45 if (context->draw_counter) {
46 context->draw_counter--;
47 uint16_t pixels = context->vram[context->draw_source++];
48 for (int i = 0; i < 4; i++)
49 {
50 uint8_t pixel = ((pixels >> ((3-i) * 4)) & 0xF) | context->palpriority;
51 context->drawbuffer[context->draw_dest++] = pixel;
52 }
53 } else {
54 //00VV VVVV VVHH HHHH
55 uint16_t vpos = (context->vscroll & 0x7FF) + context->vcounter - 16;
56 uint16_t vmask = (context->vscroll >> 2) & 0x3E00;
57 uint16_t vcoarse = (vpos << 3) & 0x3FC0;
58 uint16_t vfine = vpos & 7;
59 uint16_t hcoarse = ((context->hscroll >> 3) + context->hcounter/6) & 0x3F;
60 uint16_t tableaddress = hcoarse | (vcoarse & ~vmask) | ((context->vscroll << 3) & vmask);
61 //printf("VCounter: %X, VScroll: %X, HCounter: %X, Table: %X\n", context->vcounter, context->vscroll, context->hcounter, tableaddress);
62 uint16_t entry = context->vram[tableaddress];
63 context->draw_source = (entry & 0x3FF) * 16;
64 if (entry & 0x1000) {
65 context->draw_source += 14 - vfine * 2;
66 } else {
67 context->draw_source += vfine * 2;
68 }
69 context->palpriority = entry >> 9 & 0x70;
70 context->draw_counter = 2;
71 //TODO: handle horizontal flip
72 }
73 //TODO: Scan sprite table
74 } else {
75 //TODO: Render sprites
76 }
77 }
29 //Draw to framebuffer 78 //Draw to framebuffer
30 if (context->vcounter > 8 && context->vcounter < 249 && context->hcounter < 320) { 79 if (context->vcounter > 8 && context->vcounter < 249 && context->hcounter < 320) {
31 if (!context->hcounter && context->vcounter == 9) { 80 if (!context->hcounter && context->vcounter == 9) {
32 context->framebuffer = system_get_framebuffer(&context->pitch); 81 context->framebuffer = system_get_framebuffer(&context->pitch);
33 //pitch is in terms of bytes, but we want it in terms of pixels 82 //pitch is in terms of bytes, but we want it in terms of pixels
94 void vdp_write_data(vdp *context, uint16_t value) 143 void vdp_write_data(vdp *context, uint16_t value)
95 { 144 {
96 context->fifo = value; 145 context->fifo = value;
97 context->status |= VDP_STATUS_FIFO; 146 context->status |= VDP_STATUS_FIFO;
98 } 147 }
148
149 void vdp_write_hscroll(vdp *context, uint16_t value)
150 {
151 context->hscroll = value & 0x1FF;
152 if (value & 0x8000) {
153 context->status |= VDP_STATUS_ENABLED;
154 } else {
155 context->status &= ~VDP_STATUS_ENABLED;
156 }
157 }