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view src/vbe.c @ 1:a826bf0fb169

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author John Tsiombikas <nuclear@member.fsf.org>
date Sat, 05 Apr 2014 09:05:26 +0300
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1 #include <stdio.h>
2 #include <string.h>
3 #include "vbe.h"
4 #include "dpmi.h"
5
6 /* VGA DAC registers used for palette setting in 8bpp modes */
7 #define VGA_DAC_STATE 0x3c7
8 #define VGA_DAC_ADDR_RD 0x3c7
9 #define VGA_DAC_ADDR_WR 0x3c8
10 #define VGA_DAC_DATA 0x3c9
11
12 #define MODE_LFB (1 << 14)
13
14
15 struct vbe_info *vbe_get_info(void)
16 {
17 static unsigned short info_block_seg;
18 static struct vbe_info *info;
19 struct dpmi_real_regs regs;
20
21 if(!info) {
22 /* allocate 32 paragraphs (512 bytes) */
23 info_block_seg = dpmi_alloc(32);
24 info = (struct vbe_info*)(info_block_seg << 4);
25 }
26
27 memcpy(info->sig, "VBE2", 4);
28
29 memset(&regs, 0, sizeof regs);
30 regs.es = info_block_seg;
31 regs.eax = 0x4f00;
32
33 dpmi_real_int(0x10, &regs);
34
35 return info;
36 }
37
38 struct vbe_mode_info *vbe_get_mode_info(int mode)
39 {
40 static unsigned short mode_info_seg;
41 static struct vbe_mode_info *mi;
42 struct dpmi_real_regs regs;
43
44 if(!mi) {
45 /* allocate 16 paragraphs (256 bytes) */
46 mode_info_seg = dpmi_alloc(16);
47 mi = (struct vbe_mode_info*)(mode_info_seg << 4);
48 }
49
50 memset(&regs, 0, sizeof regs);
51 regs.es = mode_info_seg;
52 regs.eax = 0x4f01;
53 regs.ecx = mode;
54 regs.es = mode_info_seg;
55
56 dpmi_real_int(0x10, &regs);
57 if(regs.eax & 0xff00) {
58 return 0;
59 }
60
61 return mi;
62 }
63
64 int vbe_set_mode(int mode)
65 {
66 struct dpmi_real_regs regs;
67
68 memset(&regs, 0, sizeof regs);
69 regs.eax = 0x4f02;
70 regs.ebx = mode;
71 dpmi_real_int(0x10, &regs);
72
73 if(regs.eax == 0x100) {
74 return -1;
75 }
76 return 0;
77 }
78
79 int vbe_set_palette_bits(int bits)
80 {
81 struct dpmi_real_regs regs;
82
83 memset(&regs, 0, sizeof regs);
84 regs.eax = 0x4f08;
85 regs.ebx = bits << 8; /* bits in bh */
86 dpmi_real_int(0x10, &regs);
87
88 if((regs.eax >> 8) & 0xff == 3) {
89 return -1;
90 }
91 return regs.ebx >> 8 & 0xff; /* new color bits in bh */
92 }
93
94 /* TODO: implement palette setting through the VBE2 interface for
95 * non-VGA displays (actually don't).
96 */
97 void vbe_set_palette(int idx, int *col, int count, int bits)
98 {
99 int i, shift = 8 - bits;
100
101 __asm {
102 mov dx, VGA_DAC_ADDR_WR
103 mov eax, idx
104 out dx, al
105 }
106
107 for(i=0; i<count; i++) {
108 unsigned char r = *col++;
109 unsigned char g = *col++;
110 unsigned char b = *col++;
111
112 if(shift) {
113 r >>= shift;
114 g >>= shift;
115 b >>= shift;
116 }
117
118 __asm {
119 mov dx, VGA_DAC_DATA
120 mov al, r
121 out dx, al
122 mov al, g
123 out dx, al
124 mov al, b
125 out dx, al
126 }
127 }
128 }
129
130 static unsigned int get_mask(int sz, int pos)
131 {
132 unsigned int i, mask = 0;
133
134 for(i=0; i<sz; i++) {
135 mask |= 1 << i;
136 }
137 return mask << pos;
138 }
139
140 void print_mode_info(FILE *fp, struct vbe_mode_info *mi)
141 {
142 fprintf(fp, "resolution: %dx%d\n", mi->xres, mi->yres);
143 fprintf(fp, "color depth: %d\n", mi->bpp);
144 fprintf(fp, "mode attributes: %x\n", mi->mode_attr);
145 fprintf(fp, "bytes per scanline: %d\n", mi->scanline_bytes);
146 fprintf(fp, "number of planes: %d\n", (int)mi->num_planes);
147 fprintf(fp, "number of banks: %d\n", (int)mi->num_banks);
148 fprintf(fp, "mem model: %d\n", (int)mi->mem_model);
149 fprintf(fp, "red bits: %d (mask: %x)\n", (int)mi->rmask_size, get_mask(mi->rmask_size, mi->rpos));
150 fprintf(fp, "green bits: %d (mask: %x)\n", (int)mi->gmask_size, get_mask(mi->gmask_size, mi->gpos));
151 fprintf(fp, "blue bits: %d (mask: %x)\n", (int)mi->bmask_size, get_mask(mi->bmask_size, mi->bpos));
152 fprintf(fp, "framebuffer address: %x\n", mi->fb_addr);
153 }