/* * Copyright 1993 by David Wexelblat * * Permission to use, copy, modify, distribute, and sell this software and its * documentation for any purpose is hereby granted without fee, provided that * the above copyright notice appear in all copies and that both that * copyright notice and this permission notice appear in supporting * documentation, and that the name of David Wexelblat not be used in * advertising or publicity pertaining to distribution of the software without * specific, written prior permission. David Wexelblat makes no representations * about the suitability of this software for any purpose. It is provided * "as is" without express or implied warranty. * * DAVID WEXELBLAT DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO * EVENT SHALL DAVID WEXELBLAT BE LIABLE FOR ANY SPECIAL, INDIRECT OR * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR * PERFORMANCE OF THIS SOFTWARE. */ /*************************************************************************/ /* * This is a oak SVGA driver for XFree86. * * Built from Xfree86 1.3 stub file. * 9/1/93 Initial version Steve Goldman sgoldman@encore.com * * This one file can be used for both the color and monochrome servers. * Remember that the monochrome server is actually using a 16-color mode, * with only one bitplane active. To distinguish between the two at * compile-time, use '#ifdef MONOVGA', etc. */ /*************************************************************************/ /* $XFree86: mit/server/ddx/x386/vga256/drivers/oak/oak_driver.c,v 2.2 1993/12/25 14:02:48 dawes Exp $ */ /* * These are X and server generic header files. */ #include "X.h" #include "input.h" #include "screenint.h" /* * These are XFree86-specific header files */ #include "compiler.h" #include "x386.h" #include "x386Priv.h" #include "xf86_OSlib.h" #include "xf86_HWlib.h" #include "vga.h" /* * Driver data structures. */ typedef struct { /* * This structure defines all of the register-level information * that must be stored to define a video mode for this chipset. * The 'vgaHWRec' member must be first, and contains all of the * standard VGA register information, as well as saved text and * font data. */ vgaHWRec std; /* good old IBM VGA */ /* * Any other registers or other data that the new chipset needs * to be saved should be defined here. The Init/Save/Restore * functions will manipulate theses fields. Examples of things * that would go here are registers that contain bank select * registers, or extended clock select bits, or extensions to * the timing registers. Use 'unsigned char' as the type for * these registers. */ unsigned char oakMisc; /* Misc register */ unsigned char oakOverflow; /* overflow register */ unsigned char oakHsync2; /* Hsync/2 start register */ unsigned char oakOverflow2; /* overflow2 register */ unsigned char oakConfig; /* config 67 vs. 77 */ unsigned char oakBCompat; /* backward compatibility */ unsigned char oakBank; /* initial bank, debug only */ } vgaOAKRec, *vgaOAKPtr; /* * Forward definitions for the functions that make up the driver. See * the definitions of these functions for the real scoop. */ static Bool OAKProbe(); static char * OAKIdent(); static void OAKClockSelect(); static void OAKEnterLeave(); static Bool OAKInit(); extern void * OAKSave(); extern void OAKRestore(); static void OAKAdjust(); #if 0 static void OAKSaveScreen(); static void OAKGetMode(); #endif /* * These are the bank select functions. There are defined in oak_bank.s */ extern void OAKSetRead(); extern void OAKSetWrite(); extern void OAKSetReadWrite(); /* * This data structure defines the driver itself. The data structure is * initialized with the functions that make up the driver and some data * that defines how the driver operates. */ vgaVideoChipRec OAK = { /* * Function pointers */ OAKProbe, OAKIdent, OAKEnterLeave, OAKInit, OAKSave, OAKRestore, OAKAdjust, NoopDDA, NoopDDA, NoopDDA, OAKSetRead, OAKSetWrite, OAKSetReadWrite, /* * This is the size of the mapped memory window, usually 64k. */ 0x10000, /* * This is the size of a video memory bank for this chipset. */ 0x10000, /* * This is the number of bits by which an address is shifted * right to determine the bank number for that address. */ 16, /* * This is the bitmask used to determine the address within a * specific bank. */ 0xFFFF, /* * These are the bottom and top addresses for reads inside a * given bank. */ 0x00000, 0x10000, /* * And corresponding limits for writes. */ 0x00000, 0x10000, /* * Whether this chipset supports a single bank register or * separate read and write bank registers. Almost all chipsets * support two banks, and two banks are almost always faster * (Trident 8900C and 9000 are odd exceptions). */ TRUE, /* two banks */ /* * If the chipset requires vertical timing numbers to be divided * by two for interlaced modes, set this to VGA_DIVIDE_VERT. */ VGA_NO_DIVIDE_VERT, /* * This is a dummy initialization for the set of vendor/option flags * that this driver supports. It gets filled in properly in the * probe function, if the probe succeeds (assuming the driver * supports any such flags). */ {0,}, /* * This specifies how the virtual width is to be rounded. The * virtual width will be rounded down the nearest multiple of * this value */ 16, }; /* * This is a convenience macro, so that entries in the driver structure * can simply be dereferenced with 'new->xxx'. */ #define new ((vgaOAKPtr)vgaNewVideoState) /* A bunch of defines that match Oak's register names so we don't use a bunch of hardcoded constants in the code. */ #define OTI_INDEX 0x3DE /* Oak extended index register */ #define OTI_R_W 0x3DF /* Oak extended r/w register */ #define OTI_CRT_CNTL 0xC /* Oak CRT COntrol Register */ #define OTI_MISC 0xD /* Oak Misc register */ #define OTI_BCOMPAT 0xE /* Oak Back compat register */ #define OTI_SEGMENT 0x11 /* Oak segment register */ #define OTI_CONFIG 0x12 /* Oak config register */ #define OTI_OVERFLOW 0x14 /* Oak overflow register */ #define OTI_HSYNC2 0x15 /* Oak hsync/2 start register */ #define OTI_OVERFLOW2 0x16 /* Oak overflow2 register */ #define OTI67 0 /* same index as ident function */ #define OTI77 1 /* same index as ident function */ static int OTI_chipset; static unsigned OAK_ExtPorts[] = { OTI_INDEX, OTI_R_W }; static int Num_OAK_ExtPorts = (sizeof(OAK_ExtPorts)/sizeof(OAK_ExtPorts[0])); /* * OAKIdent -- * * Returns the string name for supported chipset 'n'. Most drivers only * support one chipset, but multiple version may require that the driver * identify them individually (e.g. the Trident driver). The Ident function * should return a string if 'n' is valid, or NULL otherwise. The * server will call this function when listing supported chipsets, with 'n' * incrementing from 0, until the function returns NULL. The 'Probe' * function should call this function to get the string name for a chipset * and when comparing against an Xconfig-supplied chipset value. This * cuts down on the number of places errors can creep in. */ static char * OAKIdent(n) int n; { static char *chipsets[] = {"oti067","oti077"}; if (n + 1 > sizeof(chipsets) / sizeof(char *)) return(NULL); else return(chipsets[n]); } /* * OAKClockSelect -- * * This function selects the dot-clock with index 'no'. In most cases * this is done my setting the correct bits in various registers (generic * VGA uses two bits in the Miscellaneous Output Register to select from * 4 clocks). Care must be taken to protect any other bits in these * registers by fetching their values and masking off the other bits. */ static void OAKClockSelect(no) int no; { static unsigned char save1,save2; unsigned char temp; switch(no) { case CLK_REG_SAVE: /* * Here all of the registers that can be affected by * clock setting should be saved into static variables. */ save1 = inb(0x3CC); /* Any extended registers would go here */ outb(OTI_INDEX, OTI_MISC); save2 = inb(OTI_R_W); break; case CLK_REG_RESTORE: /* * Here all the previously saved registers are restored. */ outb(0x3C2, save1); /* Any extended registers would go here */ /* all the examples seem to just blast the old data in what about any other bit changes?? */ outw(OTI_INDEX, OTI_MISC | (save2 << 8)); break; default: /* * These are the generic two low-order bits of the clock select */ temp = inb(0x3CC); outb(0x3C2, ( temp & 0xF3) | ((no << 2) & 0x0C)); /* * Here is where the high order bit(s) supported by the chipset * are set. This is done by fetching the appropriate register, * masking off bits that will be changing, then shifting and * masking 'no' to set the bits as appropriate. */ outb(OTI_INDEX, OTI_MISC); temp = inb(OTI_R_W); outw(OTI_INDEX, OTI_MISC | ((( temp & 0xDF ) | (( no & 4) << 3)) << 8)); } } /* * OAKProbe -- * * This is the function that makes a yes/no decision about whether or not * a chipset supported by this driver is present or not. The server will * call each driver's probe function in sequence, until one returns TRUE * or they all fail. * * Pretty much any mechanism can be used to determine the presence of the * chipset. If there is a BIOS signature (e.g. ATI, GVGA), it can be read * via /dev/mem on most OSs, but some OSs (e.g. Mach) require special * handling, and others (e.g. Amoeba) don't allow reading the BIOS at * all. Hence, this mechanism is discouraged, if other mechanisms can be * found. If the BIOS-reading mechanism must be used, examine the ATI and * GVGA drivers for the special code that is needed. Note that the BIOS * base should not be assumed to be at 0xC0000 (although most are). Use * 'vga256InfoRec.BIOSbase', which will pick up any changes the user may * have specified in the Xconfig file. * * The preferred mechanism for doing this is via register identification. * It is important not only the chipset is detected, but also to * ensure that other chipsets will not be falsely detected by the probe * (this is difficult, but something that the developer should strive for). * For testing registers, there are a set of utility functions in the * "compiler.h" header file. A good place to find example probing code is * in the SuperProbe program, which uses algorithms from the "vgadoc2.zip" * package (available on most PC/vga FTP mirror sites, like ftp.uu.net and * wuarchive.wustl.edu). * * Once the chipset has been successfully detected, then the developer needs * to do some other work to find memory, and clocks, etc, and do any other * driver-level data-structure initialization may need to be done. */ static Bool OAKProbe() { unsigned char save, temp1; xf86ClearIOPortList(vga256InfoRec.scrnIndex); xf86AddIOPorts(vga256InfoRec.scrnIndex, Num_VGA_IOPorts, VGA_IOPorts); xf86AddIOPorts(vga256InfoRec.scrnIndex, Num_OAK_ExtPorts, OAK_ExtPorts); /* * First we attempt to figure out if one of the supported chipsets * is present. */ if (vga256InfoRec.chipset) { /* * This is the easy case. The user has specified the * chipset in the Xconfig file. All we need to do here * is a string comparison against each of the supported * names available from the Ident() function. If this * driver supports more than one chipset, there would be * nested conditionals here (see the Trident and WD drivers * for examples). */ if (!StrCaseCmp(vga256InfoRec.chipset, OAKIdent(0))) { OTI_chipset = OTI67; } else if (!StrCaseCmp(vga256InfoRec.chipset, OAKIdent(1))) { OTI_chipset = OTI77; } else return (FALSE); OAKEnterLeave(ENTER); } else { /* * OK. We have to actually test the hardware. The * EnterLeave() function (described below) unlocks access * to registers that may be locked, and for OSs that require * it, enables I/O access. So we do this before we probe, * even though we don't know for sure that this chipset * is present. */ OAKEnterLeave(ENTER); /* * Here is where all of the probing code should be placed. * The best advice is to look at what the other drivers are * doing. If you are lucky, the chipset reference will tell * how to do this. Other resources include SuperProbe/vgadoc2, * and the Ferraro book. */ /* First we see if the segment register is present */ outb(OTI_INDEX, OTI_SEGMENT); save = inb(OTI_R_W); /* I assume that one I set the index I can r/w/r/w to my hearts content */ outb(OTI_R_W, save ^ 0x11); temp1 = inb(OTI_R_W); outb(OTI_R_W, save); if (temp1 != ( save ^ 0x11 )) { /* * Turn things back off if the probe is going to fail. * Returning FALSE implies failure, and the server * will go on to the next driver. */ OAKEnterLeave(LEAVE); return(FALSE); } /* figure out which chipset */ temp1 = inb(OTI_INDEX); temp1 &= 0xE0; switch (temp1) { case 0xE0 : /* oti 57 don't know it */ ErrorF("OAK driver: OTI-57 unsupported\n"); OAKEnterLeave(LEAVE); return(FALSE); case 0x40 : /* oti 67 */ OTI_chipset = OTI67; break; case 0xA0 : /* oti 77 */ OTI_chipset = OTI77; break; default : /* don't know it */ ErrorF("OAK driver: unknown chipset\n"); OAKEnterLeave(LEAVE); return(FALSE); } } /* * If the user has specified the amount of memory in the Xconfig * file, we respect that setting. */ if (!vga256InfoRec.videoRam) { /* * Otherwise, do whatever chipset-specific things are * necessary to figure out how much memory (in kBytes) is * available. */ outb(OTI_INDEX, OTI_MISC); temp1 = inb(OTI_R_W); temp1 &= 0xC0; if (temp1 == 0xC0 ) vga256InfoRec.videoRam = 1024; else if (temp1 == 0x80 ) vga256InfoRec.videoRam = 512; else if (temp1 == 0x00 ) vga256InfoRec.videoRam = 256; else { ErrorF("OAK driver: unknown video memory\n"); OAKEnterLeave(LEAVE); return(FALSE); } } /* * Again, if the user has specified the clock values in the Xconfig * file, we respect those choices. */ if (!vga256InfoRec.clocks) { /* * This utility function will probe for the clock values. * It is passed the number of supported clocks, and a * pointer to the clock-select function. */ vgaGetClocks(8, OAKClockSelect); } /* * Last we fill in the remaining data structures. We specify * the chipset name, using the Ident() function and an appropriate * index. We set a boolean for whether or not this driver supports * banking for the Monochrome server. And we set up a list of all * the vendor flags that this driver can make use of. */ vga256InfoRec.chipset = OAKIdent(OTI_chipset); vga256InfoRec.bankedMono = TRUE; return(TRUE); } /* * OAKEnterLeave -- * * This function is called when the virtual terminal on which the server * is running is entered or left, as well as when the server starts up * and is shut down. Its function is to obtain and relinquish I/O * permissions for the SVGA device. This includes unlocking access to * any registers that may be protected on the chipset, and locking those * registers again on exit. */ static void OAKEnterLeave(enter) Bool enter; { static unsigned char save; unsigned char temp; if (enter) { xf86EnableIOPorts(vga256InfoRec.scrnIndex); /* * This is a global. The CRTC base address depends on * whether the VGA is functioning in color or mono mode. * This is just a convenient place to initialize this * variable. */ vgaIOBase = (inb(0x3CC) & 0x01) ? 0x3D0 : 0x3B0; /* * Here we deal with register-level access locks. This * is a generic VGA protection; most SVGA chipsets have * similar register locks for their extended registers * as well. */ /* Unprotect CRTC[0-7] */ outb(vgaIOBase + 4, 0x11); temp = inb(vgaIOBase + 5); outb(vgaIOBase + 5, temp & 0x7F); outb(OTI_INDEX, OTI_CRT_CNTL); temp = inb(OTI_R_W); outb(OTI_R_W, temp & 0xF0); save = temp; } else { /* * Here undo what was done above. */ outb(OTI_INDEX, OTI_CRT_CNTL); /* don't set the i/o write test bit even though we cleared it on entry */ outb(OTI_R_W, (save & 0xF7) ); /* Protect CRTC[0-7] */ outb(vgaIOBase + 4, 0x11); temp = inb(vgaIOBase + 5); outb(vgaIOBase + 5, (temp & 0x7F) | 0x80); xf86DisableIOPorts(vga256InfoRec.scrnIndex); } } /* * OAKRestore -- * * This function restores a video mode. It basically writes out all of * the registers that have previously been saved in the vgaOAKRec data * structure. * * Note that "Restore" is a little bit incorrect. This function is also * used when the server enters/changes video modes. The mode definitions * have previously been initialized by the Init() function, below. */ extern void OAKRestore(restore) vgaOAKPtr restore; { unsigned char temp; /* * Whatever code is needed to get things back to bank zero should be * placed here. Things should be in the same state as when the * Save/Init was done. */ /* put the segment regs back to zero */ outw(OTI_INDEX, OTI_SEGMENT); /* Set the OTI-Misc register. We must be sure that we aren't in one of the extended graphics modes when we are leaving X and about to call vgaHWRestore for the last time. If we don't text mode is completely fouled up. */ outb(OTI_INDEX, OTI_MISC); temp = inb(OTI_R_W) & 0x20; /* get the clock bit */ temp |= (restore->oakMisc & 0xDF); outb(OTI_R_W, temp); /* * This function handles restoring the generic VGA registers. */ vgaHWRestore(restore); /* * Code to restore any SVGA registers that have been saved/modified * goes here. Note that it is allowable, and often correct, to * only modify certain bits in a register by a read/modify/write cycle. * * A special case - when using an external clock-setting program, * this function must not change bits associated with the clock * selection. This condition can be checked by the condition: * * if (restore->std.NoClock >= 0) * restore clock-select bits. */ outb(OTI_INDEX, OTI_SEGMENT); outb(OTI_R_W, restore->oakBank); if (restore->std.NoClock >= 0) { /* restore clock-select bits. */ outw(OTI_INDEX, OTI_MISC + (restore->oakMisc << 8)); } else { /* don't restore clock-select bits. */ outb(OTI_INDEX, OTI_MISC); temp = inb(OTI_R_W) & 0x20; /* get the clock bit */ temp |= (restore->oakMisc & 0xDF); outb(OTI_R_W, temp); } outb(OTI_INDEX, OTI_BCOMPAT); temp = inb(OTI_R_W); temp &= 0xF9; temp |= (restore->oakBCompat & 0x6); outb(OTI_INDEX, OTI_CONFIG); temp = inb(OTI_R_W); temp &= 0xF7; temp |= (restore->oakConfig & 0x8); outb(OTI_R_W, temp); outw(OTI_INDEX, OTI_OVERFLOW + (restore->oakOverflow << 8)); outw(OTI_INDEX, OTI_HSYNC2 + (restore->oakHsync2 << 8)); if ( OTI_chipset == OTI77) outw(OTI_INDEX, OTI_OVERFLOW2 + (restore->oakOverflow2 << 8)); outw(0x3C4, 0x0300); /* now reenable the timing sequencer */ } /* * OAKSave -- * * This function saves the video state. It reads all of the SVGA registers * into the vgaOAKRec data structure. There is in general no need to * mask out bits here - just read the registers. */ extern void * OAKSave(save) vgaOAKPtr save; { unsigned char temp; /* * Whatever code is needed to get back to bank zero goes here. */ outb(OTI_INDEX, OTI_SEGMENT); temp = inb(OTI_R_W); /* put segment register to zero */ outb(OTI_R_W, 0); /* * This function will handle creating the data structure and filling * in the generic VGA portion. */ save = (vgaOAKPtr)vgaHWSave(save, sizeof(vgaOAKRec)); /* * The port I/O code necessary to read in the extended registers * into the fields of the vgaOAKRec structure goes here. */ save->oakBank = temp; /* this seems silly, leftover from textmode problems */ outb(OTI_INDEX, OTI_MISC); save->oakMisc = inb(OTI_R_W); outb(OTI_INDEX, OTI_CONFIG); save->oakConfig = inb(OTI_R_W); outb(OTI_INDEX, OTI_BCOMPAT); save->oakBCompat = inb(OTI_R_W); outb(OTI_INDEX, OTI_OVERFLOW); save->oakOverflow = inb(OTI_R_W); outb(OTI_INDEX, OTI_HSYNC2); save->oakHsync2 = inb(OTI_R_W); if ( OTI_chipset == OTI77) { outb(OTI_INDEX, OTI_OVERFLOW2); save->oakOverflow2 = inb(OTI_R_W); } return ((void *) save); } /* * OAKInit -- * * This is the most important function (after the Probe) function. This * function fills in the vgaOAKRec with all of the register values needed * to enable either a 256-color mode (for the color server) or a 16-color * mode (for the monochrome server). * * The 'mode' parameter describes the video mode. The 'mode' structure * as well as the 'vga256InfoRec' structure can be dereferenced for * information that is needed to initialize the mode. The 'new' macro * (see definition above) is used to simply fill in the structure. */ static Bool OAKInit(mode) DisplayModePtr mode; { if (mode->Flags & V_INTERLACE ) { /* When in interlace mode cut the vertical numbers in half. (Try and find that in the manual!) Could just set VGA_DIVIDE_VERT but we'd have to test it and do the divides here anyway. */ mode->VTotal >>= 1; mode->VDisplay >>= 1; mode->VSyncStart >>= 1; mode->VSyncEnd >>= 1; } /* * This will allocate the datastructure and initialize all of the * generic VGA registers. */ if (!vgaHWInit(mode,sizeof(vgaOAKRec))) return(FALSE); /* * Here all of the other fields of 'new' get filled in, to * handle the SVGA extended registers. It is also allowable * to override generic registers whenever necessary. * * A special case - when using an external clock-setting program, * this function must not change bits associated with the clock * selection. This condition can be checked by the condition: * * if (new->std.NoClock >= 0) * initialize clock-select bits. */ #ifndef MONOVGA /* new->std.CRTC[19] = vga256InfoRec.virtualX >> 3; /* 3 in byte mode */ /* much clearer as 0x01 than 0x41, seems odd though... */ new->std.Attribute[16] = 0x01; /* We set the fifo depth to maximum since it seems to remove screen interference at high resolution. This could probably be set to some other value for better performance. */ if ( new->std.NoClock >= 0 ) { new->oakMisc = 0x0F | ((new->std.NoClock & 0x04) << 3); } else new->oakMisc = 0x0F; /* high res mode, deep fifo */ #else if ( new->std.NoClock >= 0 ) { new->oakMisc = 0x18 | ((new->std.NoClock & 0x04) << 3); } else new->oakMisc = 0x18; /* 16 color high res mode */ #endif new->oakBank = 0; new->oakBCompat = 0x80; /* vga mode */ new->oakConfig = (OTI_chipset == OTI77 ? 0x8 : 0 ); /* set number of ram chips! */ /* 40 */ new->oakMisc |= (vga256InfoRec.videoRam == 1024 ? 0x40 : 0x00 ); new->oakMisc |= (vga256InfoRec.videoRam >= 512 ? 0x80 : 0x00 ); if (mode->Flags & V_INTERLACE ) { new->oakOverflow = 0x80 | /* V-retrace-start */ (((mode->VSyncStart ) & 0x400) >> 8 ) | /* V-blank-start */ ((((mode->VDisplay-1) ) & 0x400) >> 9 ) | /* V-total */ ((((mode->VTotal-2) ) & 0x400) >> 10 ) ; /* can set overflow2 no matter what here since restore will do the right thing */ new->oakOverflow2 = 0; /* Doc. says this is when vertical retrace will start in every odd frame in interlaced mode in characters. Hmm??? */ new->oakHsync2 = (mode->VTotal-2) >> 3; } else { new->oakOverflow = (mode->Flags & V_INTERLACE ? 0x80 : 0x00) | /* V-retrace-start */ ((mode->VSyncStart & 0x400) >> 8 ) | /* V-blank-start */ (((mode->VDisplay-1) & 0x400) >> 9 ) | /* V-total */ (((mode->VTotal-2) & 0x400) >> 10 ) ; /* can set overflow2 no matter what here since restore will do the right thing */ new->oakOverflow2 = 0; new->oakHsync2 = 0; } /* Put vertical numbers back so virtual screen doesn't get fooled. */ if (mode->Flags & V_INTERLACE ) { mode->VTotal <<= 1; mode->VDisplay <<= 1; mode->VSyncStart <<= 1; mode->VSyncEnd <<= 1; } return(TRUE); } /* * OAKAdjust -- * * This function is used to initialize the SVGA Start Address - the first * displayed location in the video memory. This is used to implement the * virtual window. */ static void OAKAdjust(x, y) int x, y; { int temp; /* * The calculation for Base works as follows: * * (y * virtX) + x ==> the linear starting pixel * * This number is divided by 8 for the monochrome server, because * there are 8 pixels per byte. * * For the color server, it's a bit more complex. There is 1 pixel * per byte. In general, the 256-color modes are in word-mode * (16-bit words). Word-mode vs byte-mode is will vary based on * the chipset - refer to the chipset databook. So the pixel address * must be divided by 2 to get a word address. In 256-color modes, * the 4 planes are interleaved (i.e. pixels 0,3,7, etc are adjacent * on plane 0). The starting address needs to be as an offset into * plane 0, so the Base address is divided by 4. * * So: * Monochrome: Base is divided by 8 * Color: * if in word mode, Base is divided by 8 * if in byte mode, Base is divided by 4 * * The generic VGA only supports 16 bits for the Starting Address. * But this is not enough for the extended memory. SVGA chipsets * will have additional bits in their extended registers, which * must also be set. */ int Base = (y * vga256InfoRec.virtualX + x + 3) >> 3; /* * These are the generic starting address registers. */ outw(vgaIOBase + 4, (Base & 0x00FF00) | 0x0C); outw(vgaIOBase + 4, ((Base & 0x00FF) << 8) | 0x0D); /* * Here the high-order bits are masked and shifted, and put into * the appropriate extended registers. */ outb(OTI_INDEX, OTI_OVERFLOW); temp = inb(OTI_R_W); temp &= 0xF7; temp |= ((Base & 0x10000) >> (5+8)); outb(OTI_R_W, temp); if ( OTI_chipset == OTI77) { outb(OTI_INDEX, OTI_OVERFLOW2); temp = inb(OTI_R_W); temp &= 0xF7; temp |= ((Base & 0x20000) >> (6 + 8)); outb(OTI_R_W, temp); } }