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annotate src/vdp.c @ 24:4c9dbfa30a66

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Implemented audio
author Michael Pavone <pavone@retrodev.com>
date Thu, 31 Mar 2016 00:07:37 -0700
parents a085f17b79e9
children 083347ccd508
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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 = context->hflip ? 0 : 12; i >= 0 && i < 16; i+= context->hflip ? 4 : -4)
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52 {
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53 uint8_t pixel = ((pixels >> i) & 0xF) | context->palpriority;
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54 context->drawbuffer[context->draw_dest ^ (context->hflip << 2)] = pixel;
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55 context->draw_dest++;
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56 }
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57 } else {
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58 //00VV VVVV VVHH HHHH
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59 uint16_t vpos = (context->vscroll & 0x7FF) + context->vcounter - 16;
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60 uint16_t vmask = (context->vscroll >> 2) & 0x3E00;
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61 uint16_t vcoarse = (vpos << 3) & 0x3FC0;
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62 uint16_t vfine = vpos & 7;
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63 uint16_t hcoarse = ((context->hscroll >> 3) + context->hcounter/6) & 0x3F;
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64 uint16_t tableaddress = hcoarse | (vcoarse & ~vmask) | ((context->vscroll << 3) & vmask);
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65 //printf("VCounter: %X, VScroll: %X, HCounter: %X, Table: %X\n", context->vcounter, context->vscroll, context->hcounter, tableaddress);
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66 uint16_t entry = context->vram[tableaddress];
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67 context->draw_source = (entry & 0x3FF) * 16;
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68 if (entry & 0x1000) {
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69 context->draw_source += 14 - vfine * 2;
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70 } else {
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71 context->draw_source += vfine * 2;
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72 }
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73 context->palpriority = entry >> 9 & 0x70;
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74 context->draw_counter = 2;
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75 context->hflip = (entry & 0x800) != 0;
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76 }
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77 if (context->status & VDP_STATUS_SPRITE_SCAN) {
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78 context->status |= VDP_STATUS_SRAM;
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79 uint16_t pos = context->sram[context->hcounter];
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80 uint16_t y = pos & 0xFF;
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81 uint16_t x = pos >> 8;
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82 uint16_t atts = context->sram[context->hcounter+1];
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83 x |= atts << 2 & 0x100;
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84 if (x | y) {
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85 uint16_t size = atts & 0x400 ? 16 : 8;
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86 if (context->vcounter >= y && context->vcounter < y + size) {
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87 uint16_t address = (atts & 0x3F) * 16;
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88 if (atts & 0x1000) {
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89 address += (size-1) * 2 - (context->vcounter - y) * 2;
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90 } else {
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91 address += (context->vcounter - y) * 2;
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92 }
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93 context->sprite_draws[context->current_draw].source = address;
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94 context->sprite_draws[context->current_draw].x = x;
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95 context->sprite_draws[context->current_draw].hflip = (atts & 0x800) != 0;
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96 context->sprite_draws[context->current_draw].palpriority = 0x80 | (atts >> 9 & 0x50);
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97 context->current_draw++;
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98 if (size == 16) {
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99 context->sprite_draws[context->current_draw].source = address + 32;
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100 context->sprite_draws[context->current_draw].x = x + 8;
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101 context->sprite_draws[context->current_draw].hflip = (atts & 0x800) != 0;
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102 context->sprite_draws[context->current_draw].palpriority = 0x80 | (atts >> 9 & 0x50);
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103 if (context->sprite_draws[context->current_draw].hflip) {
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104 context->sprite_draws[context->current_draw].x -= 8;
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105 context->sprite_draws[context->current_draw-1].x += 8;
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106 }
22
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107 }
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108 context->current_draw++;
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109 if (context->current_draw == 40) {
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110 //no more rendering capacity
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111 context->status &= ~VDP_STATUS_SPRITE_SCAN;
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112 context->current_draw = 0;
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113 }
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114 }
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115 } else {
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116 //hit sprite list terminator
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117 context->status &= ~VDP_STATUS_SPRITE_SCAN;
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118 context->current_draw = 0;
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119 }
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120 }
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121 } else {
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122 sprite_draw *draw = context->sprite_draws + (context->current_draw >> 1);
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123 if (draw->palpriority) {
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124 context->status |= VDP_STATUS_VRAM;
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125 uint16_t pixels = context->vram[draw->source + (context->current_draw & 1)];
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126 uint16_t x = draw->x - 16 + (context->hscroll & 7);
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127 for (int i = draw->hflip ? 0 : 12; i >= 0 && i < 16; i+= draw->hflip ? 4 : -4, x++)
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128 {
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129 uint8_t pixel = (pixels >> i) & 0xF;
22
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130 if (pixel && x < 328 && ((draw->palpriority & 0x40) || !(context->drawbuffer[x] & 0x40))) {
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131 context->drawbuffer[x ^ (draw->hflip << 2)] = pixel | draw->palpriority;
22
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132 }
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133 }
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134 if (context->current_draw & 1) {
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parents: 21
diff changeset
135 draw->palpriority = 0;
407725d9a02f Implemented sprite drawing. Added small sprite example.
Michael Pavone <pavone@retrodev.com>
parents: 21
diff changeset
136 } else {
407725d9a02f Implemented sprite drawing. Added small sprite example.
Michael Pavone <pavone@retrodev.com>
parents: 21
diff changeset
137 draw->x += 4;
407725d9a02f Implemented sprite drawing. Added small sprite example.
Michael Pavone <pavone@retrodev.com>
parents: 21
diff changeset
138 }
407725d9a02f Implemented sprite drawing. Added small sprite example.
Michael Pavone <pavone@retrodev.com>
parents: 21
diff changeset
139 }
407725d9a02f Implemented sprite drawing. Added small sprite example.
Michael Pavone <pavone@retrodev.com>
parents: 21
diff changeset
140 context->current_draw++;
19
04fc17376999 Sort of working tile rendering and tile test ROM
Michael Pavone <pavone@retrodev.com>
parents: 11
diff changeset
141 }
04fc17376999 Sort of working tile rendering and tile test ROM
Michael Pavone <pavone@retrodev.com>
parents: 11
diff changeset
142 }
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
143 //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
144 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
145 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
146 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
147 //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
148 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
149 }
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 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
151 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
152 *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
153 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
154 *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
155 } 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
156 //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
157 *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
158 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
159 *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
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 } 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
162 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
163 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
164 }
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
165 //Handle the FIFO
8
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
166 if (context->status & VDP_STATUS_FIFO) {
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
167 switch (context->fifo_dest)
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
168 {
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
169 case FIFO_DEST_VRAM:
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
170 if (!(context->status & VDP_STATUS_VRAM)) {
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
171 context->vram[context->dest_offset++] = context->fifo;
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
172 context->dest_offset &= sizeof(context->vram)/2-1;
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
173 context->status &= ~VDP_STATUS_FIFO;
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
174 }
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
175 break;
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
176 case FIFO_DEST_SRAM:
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
177 if (!(context->status & VDP_STATUS_SRAM)) {
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
178 context->sram[context->dest_offset++] = context->fifo;
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
179 context->dest_offset &= sizeof(context->sram)/2-1;
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
180 context->status &= ~VDP_STATUS_FIFO;
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
181 }
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
182 break;
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
183 case FIFO_DEST_CRAM:
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
184 context->cram[context->dest_offset++] = context->fifo;
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
185 context->dest_offset &= sizeof(context->cram)/2-1;
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
186 context->status &= ~VDP_STATUS_FIFO;
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
187 break;
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 }
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
190 context->cycles += context->clock_inc;
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
191 }
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
192 }
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
193 void vdp_write_address(vdp *context, uint16_t value)
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
194 {
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
195 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
196 if (!(value & 0x8000)) {
8
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
197 context->fifo_dest = FIFO_DEST_VRAM;
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
198 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
199 } else if ((value & 0xFF00) == 0xFE00) {
8
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
200 context->fifo_dest = FIFO_DEST_SRAM;
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
201 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
202 } else if ((value & 0xFF00) == 0xFF00) {
8
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
203 context->fifo_dest = FIFO_DEST_CRAM;
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
204 context->dest_offset = (value & (sizeof(context->cram) -1))/2;
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 }
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
207
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
208 void vdp_write_data(vdp *context, uint16_t value)
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
209 {
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
210 context->fifo = value;
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
211 context->status |= VDP_STATUS_FIFO;
5176efdda5ae Initial work on VDP emulation
Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
212 }
19
04fc17376999 Sort of working tile rendering and tile test ROM
Michael Pavone <pavone@retrodev.com>
parents: 11
diff changeset
213
04fc17376999 Sort of working tile rendering and tile test ROM
Michael Pavone <pavone@retrodev.com>
parents: 11
diff changeset
214 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
215 {
04fc17376999 Sort of working tile rendering and tile test ROM
Michael Pavone <pavone@retrodev.com>
parents: 11
diff changeset
216 context->hscroll = value & 0x1FF;
04fc17376999 Sort of working tile rendering and tile test ROM
Michael Pavone <pavone@retrodev.com>
parents: 11
diff changeset
217 if (value & 0x8000) {
04fc17376999 Sort of working tile rendering and tile test ROM
Michael Pavone <pavone@retrodev.com>
parents: 11
diff changeset
218 context->status |= VDP_STATUS_ENABLED;
04fc17376999 Sort of working tile rendering and tile test ROM
Michael Pavone <pavone@retrodev.com>
parents: 11
diff changeset
219 } else {
04fc17376999 Sort of working tile rendering and tile test ROM
Michael Pavone <pavone@retrodev.com>
parents: 11
diff changeset
220 context->status &= ~VDP_STATUS_ENABLED;
04fc17376999 Sort of working tile rendering and tile test ROM
Michael Pavone <pavone@retrodev.com>
parents: 11
diff changeset
221 }
04fc17376999 Sort of working tile rendering and tile test ROM
Michael Pavone <pavone@retrodev.com>
parents: 11
diff changeset
222 }