1vga_getmodeinfo(3) Svgalib User Manual vga_getmodeinfo(3)
2
6 vga_getmodeinfo - returns pointer to mode information structure for a
7 mode
8
10 #include <vga.h>
11 vga_modeinfo *vga_getmodeinfo(int mode );
13
16 The function returns a pointer to a statical allocated mode information
17 structure which is filled out with details for a video mode mode.
18 #include <vga.h> defines vga_modeinfo as
20 typedef struct {
22 int width;
23 int height;
24 int bytesperpixel;
25 int colors;
26 int linewidth;
27 int maxlogicalwidth;
28 int startaddressrange;
29 int maxpixels;
30 int haveblit;
31 int flags;
32 /* Extended fields, not always available: */
33 int chiptype;
34 int memory;
35 int linewidth_unit;
36 char *linear_aperture;
37 int aperture_size;
38 void (*set_aperture_page) (int page);
39 void *extensions;
40 } vga_modeinfo;
41 If the given mode is out of range, NULL is returned. Beware, even when
43 vga_getmodeinfo() returns details about a certain mode, you must check
44 if it is currently available (may depend on memory size and other
45 details) with vga_hasmode (3).
46 The fields meaning in detail:
48 Basic mode details
51 width Width of mode in pixels.
52 height Height of mode in pixel lines.
54 bytesperpixel
56 Bytes per pixel. This is 1, 2, 3, or 4 (for 256, 32K & 64K, 16M,
57 16M$ modes) and 0 for planar VGA modes.
58 linewidth
60 Logical scanline width in bytes. This is the memory offset
61 between two pixels above each other in two adjacent screen
62 lines. It is not valid to assume that linewidth == width *
63 bytesperpixel in general!
64 colors The number of colors which you can display simultaneously 2, 16,
66 256, 32768, 65536, or 16777216. Generally 16 and 256 mean that
67 a color lookup table is used. 2 means that only black/white is
68 used and the others use some high/true color mode.
69 Possible modifications of the memory layout
71 maxlogicalwidth
72 The maximum logical scanline width (in bytes) which you can set
73 for this mode with vga_setlogicalwidth(3) while still expecting
74 a perfect screen image.
75 startaddressrange
77 Mask of changeable bits of start address (in pixels). All bits
78 zero in startaddressrange must also be zero in a call to
79 vga_setdisplaystart(3) when you want to avoid noisy video sig‐
80 nals.
81 Memory size
83 maxpixels
84 Maximum number of pixels that will fit in a logical screen
85 (depends on video memory).
86 Further, advanced capabilities
88 haveblit
89 Indicates whether the following bitblit functions are available.
90 It is a logical or of the following predefined values (which
91 each have only one bit set).
92 HAVE_BITBLIT
94 has vga_bitblt(3) old style accelerator function.
95 HAVE_FILLBLIT
97 has vga_fillblt(3) old style accelerator function.
98 HAVE_IMAGEBLIT
100 has vga_imageblt(3) old style accelerator function.
101 HAVE_HLINELISTBLIT
103 has vga_hlinelistblt(3) old style accelerator function.
104 HAVE_BLITWAIT
106 has vga_blitwait(3) old style accelerator function.
107 flags Miscellaneous flags. It is a logical or of the following prede‐
109 fined values (which each have only one bit set).
110 HAVE_RWPAGE
112 vga_setreadpage(3) and vga_setwritepage(3) are available
113 in this mode.
114 IS_INTERLACED
116 Mode is interlaced, which means it will tend to flicker
117 and the user might be happier if the application chooses
118 another mode.
119 IS_MODEX
121 Mode user mode X like memory layout (planar 256 colors
122 VGA mode). See vga_setmodeX(3) for some explanations.
123 IS_DYNAMICMODE
125 Dynamically loaded mode. This mode was defined in
126 /etc/vga/libvga.conf by the user. He will probably prefer
127 its usage. However, usually this should be of no interest
128 to the user.
129 CAPABLE_LINEAR
131 Mode can be set to linear addressing with vga_setlinear‐
132 addressing(3).
133 IS_LINEAR
135 Linear addressing is already enabled for this mode.
136 EXT_INFO_AVAILABLE
138 The extended fields in this information structure are set
139 to sensible information. If EXT_INFO_AVAILABLE is not set
140 you should even not access these fields as you might have
141 encountered an old version of svgalib and the fields
142 migth actually not have been allocated at all.
143 RGB_MISORDERED
145 For 16M4 modes it means that the 4 bytes per pixel actu‐
146 ally mean 0BGR rather than BGR0 as per default. For 16M
147 mode it means that the 3 bytes actually mean RGB instead
148 of BGR.
149 The first is a general limitation of Mach32, the latter
151 one of Mach32 with a ramdac of type 4. The vga_ drawing
152 functions takes this into account.
153 HAVE_EXT_SET
155 A vga_ext_set(3) is available and can be called.
156 Extended mode information
158 You must check for EXT_INFO_AVAILABLE in flags before trying to access
159 these values.
160 chiptype
162 the chiptype that was detected/set. This specifies a subtype of
163 the current vga_getcurrentchipset(3) setting whose value depends
164 on the chipset. It should be only used for debugging or inter‐
165 nally.
166 memory memory available on the SVGA card in KB.
168 linewidth_unit
170 use only a multiple of this value for set_logicalwidth(3) or
171 set_displaystart(3) to ensure graceful alignment of lines onto
172 the vga memory in this mode and for noiseless video signals.
173 linear_aperture
175 ptr to a mmaped secondary linear framebuffer (not related to the
176 use of vga_setlinearaddressing(3)) (NULL if unavailable)
177 aperture_size
179 size of the secondary framebuffer in KB. 0 if unavailable.
180 set_aperture_page
182 a function taking an int as parameter to select a page in the
183 framebuffer addressed by read/writes to this memory arey (if
184 aperture_size < memory.
185 extensions
187 pointer to additional, internal, chipset specific info (contents
188 of the EEPROM for Mach32 driver.)
189 The vgatest(6) demo displays most of this info for all supported modes.
191
194 svgalib(7), vgagl(7), libvga.config(5), vgatest(6), vga_hasmode(3),
195 vga_init(3), vga_setmode(3), vga_getcurrentmode(3), vga_getdefault‐
196 mode(3), vga_lastmodenumber(3), vga_getmodename(3), vga_getmodenum‐
197 ber(3), vga_setlogicalwidth(3), vga_bitblt(3), vga_fillblt(3),
198 vga_imageblt(3), vga_hlinelistblt(3), vga_blitwait(3), vga_setmodeX(3),
199 vga_getcurrentchipset(3), vga_ext_set(3), vga_setlinearaddressing(3)
200
203 This manual page was edited by Michael Weller <eowmob@exp-math.uni-
204 essen.de>. The exact source of the referenced function as well as of
205 the original documentation is unknown.
206 It is very likely that both are at least to some extent are due to Harm
208 Hanemaayer <H.Hanemaayer@inter.nl.net>.
209 Occasionally this might be wrong. I hereby asked to be excused by the
211 original author and will happily accept any additions or corrections to
212 this first version of the svgalib manual.
213Svgalib (>= 1.2.11) 27 July 1997 vga_getmodeinfo(3)