// ============================================================================================ // // Copyright (C) 2002 Jeroen Janssen // // This library is free software; you can redistribute it and/or // modify it under the terms of the GNU Lesser General Public // License as published by the Free Software Foundation; either // version 2 of the License, or (at your option) any later version. // // This library is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU // Lesser General Public License for more details. // // You should have received a copy of the GNU Lesser General Public // License along with this library; if not, write to the Free Software // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA // // ============================================================================================ // // This VBE is part of the VGA Bios specific to the plex86/bochs Emulated VGA card. // You can NOT drive any physical vga card with it. // // ============================================================================================ // // This VBE Bios is based on information taken from : // - VESA BIOS EXTENSION (VBE) Core Functions Standard Version 3.0 located at www.vesa.org // // ============================================================================================ /* * Oracle LGPL Disclaimer: For the avoidance of doubt, except that if any license choice * other than GPL or LGPL is available it will apply instead, Oracle elects to use only * the Lesser General Public License version 2.1 (LGPLv2) at this time for any software where * a choice of LGPL license versions is made available with the language indicating * that LGPLv2 or any later version may be used, or where a choice of which version * of the LGPL is applied is otherwise unspecified. */ // Use VBE new dynamic mode list. Note that without this option, no // checks are currently done to make sure that modes fit into the // framebuffer! #define VBE_NEW_DYN_LIST #include #include #include "vbe.h" #include "vgadefs.h" #include "inlines.h" // disable VESA/VBE2 check in vbe info //#define VBE2_NO_VESA_CHECK // use bytewise i/o (Longhorn beta issue, not in released Vista) #define VBE_BYTEWISE_IO #ifdef VBE_BYTEWISE_IO extern void do_out_dx_ax(); #pragma aux do_out_dx_ax "*"; extern void out_w(uint16_t port, uint16_t value); #pragma aux out_w = \ "call do_out_dx_ax" \ parm [dx] [ax] modify nomemory; extern void do_in_ax_dx(); #pragma aux do_in_ax_dx "*"; extern uint16_t in_w(uint16_t port); #pragma aux in_w = \ "call do_in_ax_dx" \ parm [dx] value [ax] modify nomemory; #else #define out_w outw #define in_w inw #endif /* VESA signatures as integer constants. */ #define SIG_VBE2 0x32454256 /* 'VBE2' */ #define SIG_VESA 0x41534556 /* 'VESA' */ /* Implemented in assembler. */ extern void __cdecl vga_compat_setup(void); extern void dispi_set_enable(uint16_t enable); extern void dispi_set_bank(uint16_t bank); extern uint16_t __cdecl dispi_get_max_bpp(void); extern void __cdecl dispi_set_bank_farcall(void); // The current OEM Software Revision of this VBE Bios #define VBE_OEM_SOFTWARE_REV 0x0003 // FIXME: 'merge' these (c) etc strings with the vgabios.c strings? char vbebios_copyright[] = "VirtualBox VESA BIOS"; char vbebios_vendor_name[] = VBOX_VENDOR; char vbebios_product_name[] = VBOX_PRODUCT " VBE Adapter"; char vbebios_product_revision[] = VBOX_PRODUCT " Version " VBOX_VERSION_STRING; char vbebios_info_string[] = "VirtualBox VBE Display Adapter enabled\r\n\r\n"; char no_vbebios_info_string[] = "No VirtualBox VBE support available!\r\n\r\n"; #ifdef VGA_DEBUG char msg_vbe_init[] = "VirtualBox Version " VBOX_VERSION_STRING " VBE Display Adapter\r\n"; #endif static void dispi_set_xres(uint16_t xres) { #ifdef VGA_DEBUG printf("vbe_set_xres: %04x\n", xres); #endif out_w(VBE_DISPI_IOPORT_INDEX, VBE_DISPI_INDEX_XRES); out_w(VBE_DISPI_IOPORT_DATA, xres); } static void dispi_set_yres(uint16_t yres) { #ifdef VGA_DEBUG printf("vbe_set_yres: %04x\n", yres); #endif out_w(VBE_DISPI_IOPORT_INDEX, VBE_DISPI_INDEX_YRES); out_w(VBE_DISPI_IOPORT_DATA, yres); } static uint16_t dispi_get_yres(void) { out_w(VBE_DISPI_IOPORT_INDEX, VBE_DISPI_INDEX_YRES); return in_w(VBE_DISPI_IOPORT_DATA); } static void dispi_set_bpp(uint16_t bpp) { #ifdef VGA_DEBUG printf("vbe_set_bpp: %02x\n", bpp); #endif out_w(VBE_DISPI_IOPORT_INDEX, VBE_DISPI_INDEX_BPP); out_w(VBE_DISPI_IOPORT_DATA, bpp); } static uint16_t dispi_get_bpp(void) { out_w(VBE_DISPI_IOPORT_INDEX, VBE_DISPI_INDEX_BPP); return in_w(VBE_DISPI_IOPORT_DATA); } static void dispi_set_virt_width(uint16_t vwidth) { #ifdef VGA_DEBUG printf("vbe_set_virt_width: %04x\n", vwidth); #endif out_w(VBE_DISPI_IOPORT_INDEX, VBE_DISPI_INDEX_VIRT_WIDTH); out_w(VBE_DISPI_IOPORT_DATA, vwidth); } static uint16_t dispi_get_virt_width(void) { out_w(VBE_DISPI_IOPORT_INDEX, VBE_DISPI_INDEX_VIRT_WIDTH); return in_w(VBE_DISPI_IOPORT_DATA); } static uint16_t dispi_get_virt_height(void) { out_w(VBE_DISPI_IOPORT_INDEX, VBE_DISPI_INDEX_VIRT_HEIGHT); return in_w(VBE_DISPI_IOPORT_DATA); } uint16_t in_word(uint16_t port, uint16_t addr) { outw(port, addr); return inw(port); } #ifdef VBE_NEW_DYN_LIST uint8_t in_byte(uint16_t port, uint16_t addr) { outw(port, addr); return inb(port); } #endif /* Display "chip" identification helpers. */ static uint16_t dispi_get_id(void) { outw(VBE_DISPI_IOPORT_INDEX, VBE_DISPI_INDEX_ID); return inw(VBE_DISPI_IOPORT_DATA); } static void dispi_set_id(uint16_t chip_id) { outw(VBE_DISPI_IOPORT_INDEX, VBE_DISPI_INDEX_ID); outw(VBE_DISPI_IOPORT_DATA, chip_id); } /* VBE Init - Initialise the VESA BIOS Extension (VBE) support * This function does a sanity check on the host side display code interface. */ void vbe_init(void) { dispi_set_id(VBE_DISPI_ID0); if (dispi_get_id() == VBE_DISPI_ID0) { /* VBE support was detected. */ write_byte(BIOSMEM_SEG, BIOSMEM_VBE_FLAG, 1); dispi_set_id(VBE_DISPI_ID4); } #ifdef DEBUG_VGA printf(msg_vbe_init); #endif } /* Find the offset of the desired mode, given its number. */ #ifdef VBE_NEW_DYN_LIST static uint16_t mode_info_find_mode(uint16_t mode, Boolean using_lfb) { uint16_t sig, vmode, attrs; uint16_t cur_info_ofs; /* Current offset in mode list. */ /* Read and check the VBE Extra Data signature. */ sig = in_word(VBE_EXTRA_PORT, 0); if (sig != VBEHEADER_MAGIC) { #ifdef DEBUG_VGA printf("Signature NOT found! %x\n", sig); #endif return 0; } cur_info_ofs = sizeof(VBEHeader); vmode = in_word(VBE_EXTRA_PORT, cur_info_ofs + offsetof(ModeInfoListItem, mode)/*&cur_info->mode*/); while (vmode != VBE_VESA_MODE_END_OF_LIST) { attrs = in_word(VBE_EXTRA_PORT, /*&cur_info->info.ModeAttributes*/cur_info_ofs + offsetof(ModeInfoListItem, info.ModeAttributes) ); if (vmode == mode) { if (!using_lfb) return cur_info_ofs; else if (attrs & VBE_MODE_ATTRIBUTE_LINEAR_FRAME_BUFFER_MODE) return cur_info_ofs; else { cur_info_ofs += sizeof(ModeInfoListItem); vmode = in_word(VBE_EXTRA_PORT, /*&cur_info->mode*/cur_info_ofs + offsetof(ModeInfoListItem, mode)); } } else { cur_info_ofs += sizeof(ModeInfoListItem); vmode = in_word(VBE_EXTRA_PORT, /*&cur_info->mode*/cur_info_ofs + offsetof(ModeInfoListItem, mode)); } } return 0; } #else static ModeInfoListItem* mode_info_find_mode(uint16_t mode, Boolean using_lfb) { ModeInfoListItem *cur_info = &mode_info_list; while (cur_info->mode != VBE_VESA_MODE_END_OF_LIST) { if (cur_info->mode == mode) { if (!using_lfb) return cur_info; else if (cur_info->info.ModeAttributes & VBE_MODE_ATTRIBUTE_LINEAR_FRAME_BUFFER_MODE) return cur_info; else cur_info++; } else cur_info++; } return 0; } #endif #ifndef VBOX ; VBE Display Info - Display information on screen about the VBE vbe_display_info: call _vbe_has_vbe_display test ax, ax jz no_vbe_flag mov ax, #0xc000 mov ds, ax mov si, #_vbebios_info_string jmp _display_string no_vbe_flag: mov ax, #0xc000 mov ds, ax mov si, #_no_vbebios_info_string jmp _display_string #endif /** Function 00h - Return VBE Controller Information * * Input: * AX = 4F00h * ES:DI = Pointer to buffer in which to place VbeInfoBlock structure * (VbeSignature should be VBE2 when VBE 2.0 information is desired and * the info block is 512 bytes in size) * Output: * AX = VBE Return Status * */ void vbe_biosfn_return_controller_information(uint16_t STACK_BASED *AX, uint16_t ES, uint16_t DI) { uint16_t status; uint16_t vbe2_info; uint16_t cur_mode = 0; uint16_t cur_ptr=34; #ifdef VBE_NEW_DYN_LIST uint16_t cur_info_ofs; uint16_t sig, vmode; #else ModeInfoListItem *cur_info = &mode_info_list; #endif uint16_t max_bpp = dispi_get_max_bpp(); VbeInfoBlock __far *info_block; info_block = ES :> (VbeInfoBlock *)DI; #ifdef VBE_NEW_DYN_LIST /* Read VBE Extra Data signature */ sig = in_word(VBE_EXTRA_PORT, 0); if (sig != VBEHEADER_MAGIC) { *AX = 0x0100; #ifdef DEBUG_VGA printf("Signature NOT found\n"); #endif return; } cur_info_ofs = sizeof(VBEHeader); #endif status = *AX; #ifdef VGA_DEBUG printf("VBE vbe_biosfn_return_vbe_info ES%x DI%x AX%x\n",ES,DI,status); #endif vbe2_info = 0; /* Don't use a local copy of VbeInfoBlock on the stack; it's too big. * The Ubuntu 8.04 64 bits splash screen emulator can't handle this. */ #ifdef VBE2_NO_VESA_CHECK #else /* !VBE2_NO_VESA_CHECK */ // check for VBE2 signature if (info_block->VbeSignature.Sig32 == SIG_VBE2 || info_block->VbeSignature.Sig32 == SIG_VESA) { vbe2_info = 1; #ifdef VGA_DEBUG printf("VBE correct VESA/VBE2 signature found\n"); #endif } #endif /* !VBE2_NO_VESA_CHECK */ /* VBE Signature - the compiler will optimize this into something sane. */ info_block->VbeSignature.SigChr[0] = 'V'; info_block->VbeSignature.SigChr[1] = 'E'; info_block->VbeSignature.SigChr[2] = 'S'; info_block->VbeSignature.SigChr[3] = 'A'; /* VBE Version supported. */ info_block->VbeVersion = 0x0200; /* Version 2.0. */ /* OEM String. */ info_block->OemString.Ptr = &vbebios_copyright; /* Capabilities if this implementation. */ info_block->Capabilities[0] = VBE_CAPABILITY_8BIT_DAC; info_block->Capabilities[1] = 0; info_block->Capabilities[2] = 0; info_block->Capabilities[3] = 0; /* Video mode list pointer (dynamically generated). */ info_block->VideoModePtr_Seg = ES; info_block->VideoModePtr_Off = DI + 34; /* Total controller memory in 64K units. */ info_block->TotalMemory = in_word(VBE_EXTRA_PORT, 0xffff); if (vbe2_info) { /* OEM information. */ info_block->OemSoftwareRev = VBE_OEM_SOFTWARE_REV; info_block->OemVendorName.Ptr = &vbebios_vendor_name; info_block->OemProductName.Ptr = &vbebios_product_name; info_block->OemProductRev.Ptr = &vbebios_product_revision; } #ifdef VBE_NEW_DYN_LIST do { uint8_t data_b; data_b = in_byte(VBE_EXTRA_PORT, cur_info_ofs + offsetof(ModeInfoListItem, info.BitsPerPixel) /*&cur_info->info.BitsPerPixel*/); if (data_b <= max_bpp) { vmode = in_word(VBE_EXTRA_PORT, cur_info_ofs + offsetof(ModeInfoListItem, mode)/*&cur_info->mode*/); #ifdef VGA_DEBUG printf("VBE found mode %x => %x\n", vmode, cur_mode); #endif write_word(ES, DI + cur_ptr, vmode); cur_mode++; cur_ptr+=2; } cur_info_ofs += sizeof(ModeInfoListItem); vmode = in_word(VBE_EXTRA_PORT, cur_info_ofs + offsetof(ModeInfoListItem, mode)/*&cur_info->mode*/); } while (vmode != VBE_VESA_MODE_END_OF_LIST); // Add vesa mode list terminator write_word(ES, DI + cur_ptr, vmode); #else do { if (cur_info->info.BitsPerPixel <= max_bpp) { #ifdef VGA_DEBUG printf("VBE found mode %x => %x\n", cur_info->mode,cur_mode); #endif write_word(ES, DI + cur_ptr, cur_info->mode); cur_mode++; cur_ptr += 2; } cur_info++; } while (cur_info->mode != VBE_VESA_MODE_END_OF_LIST); // Add vesa mode list terminator write_word(ES, DI + cur_ptr, cur_info->mode); #endif // VBE_NEW_DYN_LIST *AX = 0x004F; } /** Function 01h - Return VBE Mode Information * * Input: * AX = 4F01h * CX = Mode Number * ES:DI = Pointer to buffer in which to place ModeInfoBlock structure * Output: * AX = VBE Return Status * */ void vbe_biosfn_return_mode_information(uint16_t STACK_BASED *AX, uint16_t CX, uint16_t ES, uint16_t DI) { uint16_t result = 0x0100; #ifdef VBE_NEW_DYN_LIST uint16_t cur_info_ofs; #else ModeInfoListItem *cur_info; #endif Boolean using_lfb; uint8_t win_attr; #ifdef VGA_DEBUG printf("VBE vbe_biosfn_return_mode_information ES%x DI%x CX%x\n",ES,DI,CX); #endif using_lfb = ((CX & VBE_MODE_LINEAR_FRAME_BUFFER) == VBE_MODE_LINEAR_FRAME_BUFFER); CX = (CX & 0x1ff); #ifdef VBE_NEW_DYN_LIST cur_info_ofs = mode_info_find_mode(CX, using_lfb); if (cur_info_ofs) { uint16_t i; #else cur_info = mode_info_find_mode(CX, using_lfb); if (cur_info != 0) { #endif #ifdef VGA_DEBUG printf("VBE found mode %x\n",CX); #endif memsetb(ES, DI, 0, 256); // The mode info size is fixed #ifdef VBE_NEW_DYN_LIST for (i = 0; i < sizeof(ModeInfoBlockCompact); i++) { uint8_t b; b = in_byte(VBE_EXTRA_PORT, cur_info_ofs + offsetof(ModeInfoListItem, info) + i/*(char *)(&(cur_info->info)) + i*/); write_byte(ES, DI + i, b); } #else memcpyb(ES, DI, 0xc000, &(cur_info->info), sizeof(ModeInfoBlockCompact)); #endif win_attr = read_byte(ES, DI + offsetof(ModeInfoBlock, WinAAttributes)); if (win_attr & VBE_WINDOW_ATTRIBUTE_RELOCATABLE) { write_word(ES, DI + offsetof(ModeInfoBlock, WinFuncPtr), (uint16_t)(dispi_set_bank_farcall)); // If BIOS not at 0xC000 -> boom write_word(ES, DI + offsetof(ModeInfoBlock, WinFuncPtr) + 2, 0xC000); } // Update the LFB physical address which may change at runtime out_w(VBE_DISPI_IOPORT_INDEX, VBE_DISPI_INDEX_FB_BASE_HI); write_word(ES, DI + offsetof(ModeInfoBlock, PhysBasePtr) + 2, in_w(VBE_DISPI_IOPORT_DATA)); result = 0x4f; } else { #ifdef VGA_DEBUG printf("VBE *NOT* found mode %x\n",CX); #endif result = 0x100; } *AX = result; } /** Function 02h - Set VBE Mode * * Input: * AX = 4F02h * BX = Desired Mode to set * ES:DI = Pointer to CRTCInfoBlock structure * Output: * AX = VBE Return Status * */ void vbe_biosfn_set_mode(uint16_t STACK_BASED *AX, uint16_t BX, uint16_t ES, uint16_t DI) { uint16_t result; #ifdef VBE_NEW_DYN_LIST uint16_t cur_info_ofs; #else ModeInfoListItem *cur_info; #endif Boolean using_lfb; uint8_t no_clear; uint8_t lfb_flag; using_lfb = ((BX & VBE_MODE_LINEAR_FRAME_BUFFER) == VBE_MODE_LINEAR_FRAME_BUFFER); lfb_flag = using_lfb ? VBE_DISPI_LFB_ENABLED : 0; no_clear = ((BX & VBE_MODE_PRESERVE_DISPLAY_MEMORY) == VBE_MODE_PRESERVE_DISPLAY_MEMORY) ? VBE_DISPI_NOCLEARMEM : 0; BX = (BX & 0x1ff); // check for non vesa mode if (BX < VBE_MODE_VESA_DEFINED) { uint8_t mode; dispi_set_enable(VBE_DISPI_DISABLED); // call the vgabios in order to set the video mode // this allows for going back to textmode with a VBE call (some applications expect that to work) mode = (BX & 0xff); biosfn_set_video_mode(mode); result = 0x4f; goto leave; } #ifdef VBE_NEW_DYN_LIST cur_info_ofs = mode_info_find_mode(BX, using_lfb); if (cur_info_ofs != 0) { uint16_t xres, yres; uint8_t bpp; xres = in_word(VBE_EXTRA_PORT, cur_info_ofs + offsetof(ModeInfoListItem, info.XResolution) /*&cur_info->info.XResolution*/); yres = in_word(VBE_EXTRA_PORT, cur_info_ofs + offsetof(ModeInfoListItem, info.YResolution) /*&cur_info->info.YResolution*/); bpp = in_byte(VBE_EXTRA_PORT, cur_info_ofs + offsetof(ModeInfoListItem, info.BitsPerPixel) /*&cur_info->info.BitsPerPixel*/); #ifdef VGA_DEBUG printf("VBE found mode %x, setting:\n", BX); printf("\txres%x yres%x bpp%x\n", xres, yres, bpp); #endif #else cur_info = mode_info_find_mode(BX, using_lfb); if (cur_info != 0) { #ifdef VGA_DEBUG printf("VBE found mode %x, setting:\n", BX); printf("\txres%x yres%x bpp%x\n", cur_info->info.XResolution, cur_info->info.YResolution, cur_info->info.BitsPerPixel); #endif #endif // VBE_NEW_DYN_LIST // first disable current mode (when switching between vesa modi) dispi_set_enable(VBE_DISPI_DISABLED); #ifdef VBE_NEW_DYN_LIST if (bpp == 4) #else if (cur_info->info.BitsPerPixel == 4) #endif { biosfn_set_video_mode(0x6a); } #ifdef VBE_NEW_DYN_LIST dispi_set_bpp(bpp); dispi_set_xres(xres); dispi_set_yres(yres); #else dispi_set_bpp(cur_info->info.BitsPerPixel); dispi_set_xres(cur_info->info.XResolution); dispi_set_yres(cur_info->info.YResolution); #endif dispi_set_bank(0); dispi_set_enable(VBE_DISPI_ENABLED | no_clear | lfb_flag); vga_compat_setup(); write_word(BIOSMEM_SEG,BIOSMEM_VBE_MODE,BX); write_byte(BIOSMEM_SEG,BIOSMEM_VIDEO_CTL,(0x60 | no_clear)); result = 0x4f; } else { #ifdef VGA_DEBUG printf("VBE *NOT* found mode %x\n" , BX); #endif result = 0x100; } leave: *AX = result; } uint16_t vbe_biosfn_read_video_state_size(void) { return 9 * 2; } void vbe_biosfn_save_video_state(uint16_t ES, uint16_t BX) { uint16_t enable, i; outw(VBE_DISPI_IOPORT_INDEX,VBE_DISPI_INDEX_ENABLE); enable = inw(VBE_DISPI_IOPORT_DATA); write_word(ES, BX, enable); BX += 2; if (!(enable & VBE_DISPI_ENABLED)) return; for(i = VBE_DISPI_INDEX_XRES; i <= VBE_DISPI_INDEX_Y_OFFSET; i++) { if (i != VBE_DISPI_INDEX_ENABLE) { outw(VBE_DISPI_IOPORT_INDEX, i); write_word(ES, BX, inw(VBE_DISPI_IOPORT_DATA)); BX += 2; } } } void vbe_biosfn_restore_video_state(uint16_t ES, uint16_t BX) { uint16_t enable, i; enable = read_word(ES, BX); BX += 2; if (!(enable & VBE_DISPI_ENABLED)) { outw(VBE_DISPI_IOPORT_INDEX,VBE_DISPI_INDEX_ENABLE); outw(VBE_DISPI_IOPORT_DATA, enable); } else { outw(VBE_DISPI_IOPORT_INDEX, VBE_DISPI_INDEX_XRES); outw(VBE_DISPI_IOPORT_DATA, read_word(ES, BX)); BX += 2; outw(VBE_DISPI_IOPORT_INDEX, VBE_DISPI_INDEX_YRES); outw(VBE_DISPI_IOPORT_DATA, read_word(ES, BX)); BX += 2; outw(VBE_DISPI_IOPORT_INDEX, VBE_DISPI_INDEX_BPP); outw(VBE_DISPI_IOPORT_DATA, read_word(ES, BX)); BX += 2; outw(VBE_DISPI_IOPORT_INDEX,VBE_DISPI_INDEX_ENABLE); outw(VBE_DISPI_IOPORT_DATA, enable); for(i = VBE_DISPI_INDEX_BANK; i <= VBE_DISPI_INDEX_Y_OFFSET; i++) { outw(VBE_DISPI_IOPORT_INDEX, i); outw(VBE_DISPI_IOPORT_DATA, read_word(ES, BX)); BX += 2; } } } /** Function 04h - Save/Restore State * * Input: * AX = 4F04h * DL = 00h Return Save/Restore State buffer size * 01h Save State * 02h Restore State * CX = Requested states * ES:BX = Pointer to buffer (if DL <> 00h) * Output: * AX = VBE Return Status * BX = Number of 64-byte blocks to hold the state buffer (if DL=00h) * */ void vbe_biosfn_save_restore_state(uint16_t STACK_BASED *AX, uint16_t CX, uint16_t DX, uint16_t ES, uint16_t STACK_BASED *BX) { uint16_t result, val; result = 0x004F; switch(GET_DL()) { case 0x00: val = biosfn_read_video_state_size2(CX); #ifdef VGA_DEBUG printf("VGA state size=%x\n", val); #endif if (CX & 8) val += vbe_biosfn_read_video_state_size(); *BX = (val + 63) / 64; break; case 0x01: val = *BX; val = biosfn_save_video_state(CX, ES, val); #ifdef VGA_DEBUG printf("VGA save_state offset=%x\n", val); #endif if (CX & 8) vbe_biosfn_save_video_state(ES, val); break; case 0x02: val = *BX; val = biosfn_restore_video_state(CX, ES, val); #ifdef VGA_DEBUG printf("VGA restore_state offset=%x\n", val); #endif if (CX & 8) vbe_biosfn_restore_video_state(ES, val); break; default: // function failed result = 0x100; break; } *AX = result; } /** Function 06h - Set/Get Logical Scan Line Length * * Input: * AX = 4F06h * BL = 00h Set Scan Line Length in Pixels * = 01h Get Scan Line Length * = 02h Set Scan Line Length in Bytes * = 03h Get Maximum Scan Line Length * CX = If BL=00h Desired Width in Pixels * If BL=02h Desired Width in Bytes * (Ignored for Get Functions) * * Output: * AX = VBE Return Status * BX = Bytes Per Scan Line * CX = Actual Pixels Per Scan Line (truncated to * nearest complete pixel) * DX = Maximum Number of Scan Lines */ void vbe_biosfn_get_set_scanline_length(uint16_t STACK_BASED *AX, uint16_t STACK_BASED *BX, uint16_t STACK_BASED *CX, uint16_t STACK_BASED *DX) { uint16_t val; uint16_t result; uint8_t bpp; uint8_t subfn; uint16_t old_vw; bpp = dispi_get_bpp(); bpp = bpp == 15 ? 16 : bpp; old_vw = dispi_get_virt_width(); result = 0x004F; val = *CX; subfn = *BX & 0xFF; #ifdef VGA_DEBUG printf("VBE get/set scanline len fn=%x, CX=%x\n", subfn, *CX); #endif switch(subfn) { case 0x02: if (bpp == 4) val = val * 8; else val = val / (bpp / 8); /* fall through */ case 0x00: dispi_set_virt_width(val); /* fall through */ case 0x01: val = dispi_get_virt_width(); *CX = val; /* Width in pixels. */ if (bpp == 4) val = val / 8; else val = val * (bpp / 8); val = (val + 3) & ~3; *BX = val; /* Bytes per scanline. */ *DX = dispi_get_virt_height(); /* Height in lines. */ if (*DX < dispi_get_yres()) { dispi_set_virt_width(old_vw); result = 0x200; } break; default: // function failed result = 0x100; break; } *AX = result; }