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annotate src/vdp.c @ 22:407725d9a02f

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Implemented sprite drawing. Added small sprite example.
author Michael Pavone <pavone@retrodev.com>
date Wed, 30 Mar 2016 19:55:48 -0700
parents 91ded3b12d96
children a085f17b79e9
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8
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1 #include <stdint.h>
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2 #include <string.h>
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3 #include <stdio.h>
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4 #include "vdp.h"
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5 #include "system.h"
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6
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7 void vdp_init(vdp *context, uint32_t clock_div)
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8 {
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9 memset(context, 0, sizeof(vdp));
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10 //clock div specifies the pixel clock divider
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11 //but our emulation step is half that fast
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12 context->clock_inc = clock_div*2;
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13 context->drawbuffer = context->linebuffers;
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14 context->readbuffer = context->linebuffers+320;
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15 }
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16
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17 void vdp_run(vdp *context, uint32_t target)
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18 {
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19 while (context->cycles < target)
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20 {
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21 context->hcounter+=2;
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22 if (context->hcounter == 416) {
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23 context->hcounter = 0;
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24 context->vcounter++;
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25 if (context->vcounter == 262) {
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26 context->vcounter = 0;
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27 }
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28 }
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29 context->status &= ~(VDP_STATUS_VRAM|VDP_STATUS_SRAM);
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30 //Render to linebuffer
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31 if ((context->status & VDP_STATUS_ENABLED) && context->vcounter > 15 && context->vcounter < 240 && context->hcounter < 406) {
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32 if (context->hcounter < 246) {
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33 context->status |= VDP_STATUS_VRAM;
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34 if (!context->hcounter) {
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35 //flip linebuffers
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36 if (context->drawbuffer == context->linebuffers) {
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37 context->drawbuffer = context->linebuffers + 328;
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38 context->readbuffer = context->linebuffers;
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39 } else {
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40 context->drawbuffer = context->linebuffers;
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41 context->readbuffer = context->linebuffers + 328;
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42 }
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43 context->draw_dest = 0;
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44 //enable sprite scanning
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45 context->status |= VDP_STATUS_SPRITE_SCAN;
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46 context->current_draw = 0;
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47 }
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48 if (context->draw_counter) {
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49 context->draw_counter--;
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50 uint16_t pixels = context->vram[context->draw_source++];
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51 for (int i = 0; i < 4; i++)
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52 {
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53 uint8_t pixel = ((pixels >> ((3-i) * 4)) & 0xF) | context->palpriority;
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54 context->drawbuffer[context->draw_dest++] = pixel;
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55 }
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56 } else {
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57 //00VV VVVV VVHH HHHH
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58 uint16_t vpos = (context->vscroll & 0x7FF) + context->vcounter - 16;
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59 uint16_t vmask = (context->vscroll >> 2) & 0x3E00;
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60 uint16_t vcoarse = (vpos << 3) & 0x3FC0;
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61 uint16_t vfine = vpos & 7;
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62 uint16_t hcoarse = ((context->hscroll >> 3) + context->hcounter/6) & 0x3F;
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63 uint16_t tableaddress = hcoarse | (vcoarse & ~vmask) | ((context->vscroll << 3) & vmask);
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64 //printf("VCounter: %X, VScroll: %X, HCounter: %X, Table: %X\n", context->vcounter, context->vscroll, context->hcounter, tableaddress);
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65 uint16_t entry = context->vram[tableaddress];
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66 context->draw_source = (entry & 0x3FF) * 16;
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67 if (entry & 0x1000) {
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68 context->draw_source += 14 - vfine * 2;
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69 } else {
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70 context->draw_source += vfine * 2;
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71 }
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72 context->palpriority = entry >> 9 & 0x70;
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73 context->draw_counter = 2;
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74 //TODO: handle horizontal flip
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75 }
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76 if (context->status & VDP_STATUS_SPRITE_SCAN) {
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77 context->status |= VDP_STATUS_SRAM;
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78 uint16_t pos = context->sram[context->hcounter];
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79 uint16_t y = pos & 0xFF;
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80 uint16_t x = pos >> 8;
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81 uint16_t atts = context->sram[context->hcounter+1];
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82 x |= atts << 2 & 0x100;
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83 if (x | y) {
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84 uint16_t size = atts & 0x400 ? 16 : 8;
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85 if (context->vcounter >= y && context->vcounter < y + size) {
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86 uint16_t address = (atts & 0x3F) * 16;
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87 if (atts & 0x1000) {
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88 address += (size-1) * 2 - (context->vcounter - y) * 2;
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89 } else {
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90 address += (context->vcounter - y) * 2;
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91 }
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92 context->sprite_draws[context->current_draw].source = address;
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93 context->sprite_draws[context->current_draw].x = x;
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94 context->sprite_draws[context->current_draw].hflip = (atts & 0x800) != 0;
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95 context->sprite_draws[context->current_draw].palpriority = 0x80 | (atts >> 9 & 0x50);
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96 context->current_draw++;
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97 if (size == 16) {
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98 context->sprite_draws[context->current_draw].source = address + 32;
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99 context->sprite_draws[context->current_draw].x = x + 8;
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100 context->sprite_draws[context->current_draw].hflip = (atts & 0x800) != 0;
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101 context->sprite_draws[context->current_draw].palpriority = 0x80 | (atts >> 9 & 0x50);
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102 }
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103 context->current_draw++;
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104 if (context->current_draw == 40) {
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105 //no more rendering capacity
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106 context->status &= ~VDP_STATUS_SPRITE_SCAN;
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107 context->current_draw = 0;
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108 }
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109 }
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110 } else {
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111 //hit sprite list terminator
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112 context->status &= ~VDP_STATUS_SPRITE_SCAN;
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113 context->current_draw = 0;
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114 }
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115 }
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116 } else {
22
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117 sprite_draw *draw = context->sprite_draws + (context->current_draw >> 1);
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118 if (draw->palpriority) {
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119 context->status |= VDP_STATUS_VRAM;
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120 uint16_t pixels = context->vram[draw->source + (context->current_draw & 1)];
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121 uint16_t x = draw->x - 16 + (context->hscroll & 7);
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122 for (int i = 0; i < 4; i++, x++)
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123 {
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124 //TODO: handle horizontal flip
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125 uint8_t pixel = (pixels >> ((3-i) * 4)) & 0xF;
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126 if (pixel && x < 328 && ((draw->palpriority & 0x40) || !(context->drawbuffer[x] & 0x40))) {
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127 context->drawbuffer[x] = pixel | draw->palpriority;
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128 }
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129 }
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130 if (context->current_draw & 1) {
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131 draw->palpriority = 0;
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132 } else {
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133 draw->x += 4;
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134 }
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135 }
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136 context->current_draw++;
19
04fc17376999 Sort of working tile rendering and tile test ROM
Michael Pavone <pavone@retrodev.com>
parents: 11
diff changeset
137 }
04fc17376999 Sort of working tile rendering and tile test ROM
Michael Pavone <pavone@retrodev.com>
parents: 11
diff changeset
138 }
11
04d8efe7a1f0 Initial stab at video output and background color rendering. Fixed address decoding in address port write handler.
Michael Pavone <pavone@retrodev.com>
parents: 8
diff changeset
139 //Draw to framebuffer
04d8efe7a1f0 Initial stab at video output and background color rendering. Fixed address decoding in address port write handler.
Michael Pavone <pavone@retrodev.com>
parents: 8
diff changeset
140 if (context->vcounter > 8 && context->vcounter < 249 && context->hcounter < 320) {
04d8efe7a1f0 Initial stab at video output and background color rendering. Fixed address decoding in address port write handler.
Michael Pavone <pavone@retrodev.com>
parents: 8
diff changeset
141 if (!context->hcounter && context->vcounter == 9) {
04d8efe7a1f0 Initial stab at video output and background color rendering. Fixed address decoding in address port write handler.
Michael Pavone <pavone@retrodev.com>
parents: 8
diff changeset
142 context->framebuffer = system_get_framebuffer(&context->pitch);
04d8efe7a1f0 Initial stab at video output and background color rendering. Fixed address decoding in address port write handler.
Michael Pavone <pavone@retrodev.com>
parents: 8
diff changeset
143 //pitch is in terms of bytes, but we want it in terms of pixels
04d8efe7a1f0 Initial stab at video output and background color rendering. Fixed address decoding in address port write handler.
Michael Pavone <pavone@retrodev.com>
parents: 8
diff changeset
144 context->pitch /= sizeof(uint16_t);
04d8efe7a1f0 Initial stab at video output and background color rendering. Fixed address decoding in address port write handler.
Michael Pavone <pavone@retrodev.com>
parents: 8
diff changeset
145 }
04d8efe7a1f0 Initial stab at video output and background color rendering. Fixed address decoding in address port write handler.
Michael Pavone <pavone@retrodev.com>
parents: 8
diff changeset
146 uint16_t *dest = context->framebuffer + (context->vcounter - 9) * context->pitch + context->hcounter;
04d8efe7a1f0 Initial stab at video output and background color rendering. Fixed address decoding in address port write handler.
Michael Pavone <pavone@retrodev.com>
parents: 8
diff changeset
147 if (context->status & VDP_STATUS_ENABLED && context->vcounter > 16 && context->vcounter < 241) {
04d8efe7a1f0 Initial stab at video output and background color rendering. Fixed address decoding in address port write handler.
Michael Pavone <pavone@retrodev.com>
parents: 8
diff changeset
148 *dest = context->cram[0x3F & context->readbuffer[context->hcounter]];
04d8efe7a1f0 Initial stab at video output and background color rendering. Fixed address decoding in address port write handler.
Michael Pavone <pavone@retrodev.com>
parents: 8
diff changeset
149 dest++;
04d8efe7a1f0 Initial stab at video output and background color rendering. Fixed address decoding in address port write handler.
Michael Pavone <pavone@retrodev.com>
parents: 8
diff changeset
150 *dest = context->cram[0x3F & context->readbuffer[context->hcounter+1]];
04d8efe7a1f0 Initial stab at video output and background color rendering. Fixed address decoding in address port write handler.
Michael Pavone <pavone@retrodev.com>
parents: 8
diff changeset
151 } else {
04d8efe7a1f0 Initial stab at video output and background color rendering. Fixed address decoding in address port write handler.
Michael Pavone <pavone@retrodev.com>
parents: 8
diff changeset
152 //Display is disabled or we're in the border area, draw the background color
04d8efe7a1f0 Initial stab at video output and background color rendering. Fixed address decoding in address port write handler.
Michael Pavone <pavone@retrodev.com>
parents: 8
diff changeset
153 *dest = *context->cram;
04d8efe7a1f0 Initial stab at video output and background color rendering. Fixed address decoding in address port write handler.
Michael Pavone <pavone@retrodev.com>
parents: 8
diff changeset
154 dest++;
04d8efe7a1f0 Initial stab at video output and background color rendering. Fixed address decoding in address port write handler.
Michael Pavone <pavone@retrodev.com>
parents: 8
diff changeset
155 *dest = *context->cram;
04d8efe7a1f0 Initial stab at video output and background color rendering. Fixed address decoding in address port write handler.
Michael Pavone <pavone@retrodev.com>
parents: 8
diff changeset
156 }
04d8efe7a1f0 Initial stab at video output and background color rendering. Fixed address decoding in address port write handler.
Michael Pavone <pavone@retrodev.com>
parents: 8
diff changeset
157 } else if(!context->hcounter && context->vcounter == 249) {
04d8efe7a1f0 Initial stab at video output and background color rendering. Fixed address decoding in address port write handler.
Michael Pavone <pavone@retrodev.com>
parents: 8
diff changeset
158 system_framebuffer_updated();
04d8efe7a1f0 Initial stab at video output and background color rendering. Fixed address decoding in address port write handler.
Michael Pavone <pavone@retrodev.com>
parents: 8
diff changeset
159 context->framebuffer = NULL;
04d8efe7a1f0 Initial stab at video output and background color rendering. Fixed address decoding in address port write handler.
Michael Pavone <pavone@retrodev.com>
parents: 8
diff changeset
160 }
04d8efe7a1f0 Initial stab at video output and background color rendering. Fixed address decoding in address port write handler.
Michael Pavone <pavone@retrodev.com>
parents: 8
diff changeset
161 //Handle the FIFO
8
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
162 if (context->status & VDP_STATUS_FIFO) {
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
163 switch (context->fifo_dest)
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
164 {
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
165 case FIFO_DEST_VRAM:
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
166 if (!(context->status & VDP_STATUS_VRAM)) {
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
167 context->vram[context->dest_offset++] = context->fifo;
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
168 context->dest_offset &= sizeof(context->vram)/2-1;
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
169 context->status &= ~VDP_STATUS_FIFO;
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
170 }
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
171 break;
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
172 case FIFO_DEST_SRAM:
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
173 if (!(context->status & VDP_STATUS_SRAM)) {
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
174 context->sram[context->dest_offset++] = context->fifo;
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
175 context->dest_offset &= sizeof(context->sram)/2-1;
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
176 context->status &= ~VDP_STATUS_FIFO;
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
177 }
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
178 break;
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
179 case FIFO_DEST_CRAM:
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
180 context->cram[context->dest_offset++] = context->fifo;
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
181 context->dest_offset &= sizeof(context->cram)/2-1;
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
182 context->status &= ~VDP_STATUS_FIFO;
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
183 break;
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
184 }
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
185 }
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
186 context->cycles += context->clock_inc;
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
187 }
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
188 }
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
189 void vdp_write_address(vdp *context, uint16_t value)
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
190 {
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
191 context->status &= ~VDP_STATUS_FIFO;
11
04d8efe7a1f0 Initial stab at video output and background color rendering. Fixed address decoding in address port write handler.
Michael Pavone <pavone@retrodev.com>
parents: 8
diff changeset
192 if (!(value & 0x8000)) {
8
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
193 context->fifo_dest = FIFO_DEST_VRAM;
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
194 context->dest_offset = (value & (sizeof(context->vram) -1))/2;
11
04d8efe7a1f0 Initial stab at video output and background color rendering. Fixed address decoding in address port write handler.
Michael Pavone <pavone@retrodev.com>
parents: 8
diff changeset
195 } else if ((value & 0xFF00) == 0xFE00) {
8
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
196 context->fifo_dest = FIFO_DEST_SRAM;
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
197 context->dest_offset = (value & (sizeof(context->sram) -1))/2;
11
04d8efe7a1f0 Initial stab at video output and background color rendering. Fixed address decoding in address port write handler.
Michael Pavone <pavone@retrodev.com>
parents: 8
diff changeset
198 } else if ((value & 0xFF00) == 0xFF00) {
8
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
199 context->fifo_dest = FIFO_DEST_CRAM;
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
200 context->dest_offset = (value & (sizeof(context->cram) -1))/2;
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
201 }
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
202 }
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
203
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
204 void vdp_write_data(vdp *context, uint16_t value)
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
205 {
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
206 context->fifo = value;
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
207 context->status |= VDP_STATUS_FIFO;
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
208 }
19
04fc17376999 Sort of working tile rendering and tile test ROM
Michael Pavone <pavone@retrodev.com>
parents: 11
diff changeset
209
04fc17376999 Sort of working tile rendering and tile test ROM
Michael Pavone <pavone@retrodev.com>
parents: 11
diff changeset
210 void vdp_write_hscroll(vdp *context, uint16_t value)
04fc17376999 Sort of working tile rendering and tile test ROM
Michael Pavone <pavone@retrodev.com>
parents: 11
diff changeset
211 {
04fc17376999 Sort of working tile rendering and tile test ROM
Michael Pavone <pavone@retrodev.com>
parents: 11
diff changeset
212 context->hscroll = value & 0x1FF;
04fc17376999 Sort of working tile rendering and tile test ROM
Michael Pavone <pavone@retrodev.com>
parents: 11
diff changeset
213 if (value & 0x8000) {
04fc17376999 Sort of working tile rendering and tile test ROM
Michael Pavone <pavone@retrodev.com>
parents: 11
diff changeset
214 context->status |= VDP_STATUS_ENABLED;
04fc17376999 Sort of working tile rendering and tile test ROM
Michael Pavone <pavone@retrodev.com>
parents: 11
diff changeset
215 } else {
04fc17376999 Sort of working tile rendering and tile test ROM
Michael Pavone <pavone@retrodev.com>
parents: 11
diff changeset
216 context->status &= ~VDP_STATUS_ENABLED;
04fc17376999 Sort of working tile rendering and tile test ROM
Michael Pavone <pavone@retrodev.com>
parents: 11
diff changeset
217 }
04fc17376999 Sort of working tile rendering and tile test ROM
Michael Pavone <pavone@retrodev.com>
parents: 11
diff changeset
218 }