Bit8u VESA_ScanLineLength(Bit8u subcall,Bit16u val, Bit16u & bytes,Bit16u & pixels,Bit16u & lines) {
// offset register: virtual scanline length
Bitu pixels_per_offset;
Bitu bytes_per_offset = 8;
Bitu vmemsize = vga.vmemsize;
Bitu new_offset = vga.config.scan_len;
Bitu screen_height = CurMode->sheight;
switch (CurMode->type) {
case M_TEXT:
vmemsize = 0x8000; // we have only the 32kB window here
screen_height = CurMode->theight;
pixels_per_offset = 16; // two characters each 8 pixels wide
bytes_per_offset = 4; // 2 characters + 2 attributes
break;
case M_LIN4:
pixels_per_offset = 16;
break;
case M_LIN8:
pixels_per_offset = 8;
break;
case M_LIN15:
case M_LIN16:
pixels_per_offset = 4;
break;
case M_LIN32:
pixels_per_offset = 2;
break;
default:
return VESA_MODE_UNSUPPORTED;
}
switch (subcall) {
case 0x00: // set scan length in pixels
new_offset = val / pixels_per_offset;
if (val % pixels_per_offset) new_offset++;
if (new_offset > S3_MAX_OFFSET)
return VESA_HW_UNSUPPORTED; // scanline too long
vga.config.scan_len = new_offset;
VGA_CheckScanLength();
break;
case 0x01: // get current scanline length
// implemented at the end of this function
break;
case 0x02: // set scan length in bytes
new_offset = val / bytes_per_offset;
if (val % bytes_per_offset) new_offset++;
if (new_offset > S3_MAX_OFFSET)
return VESA_HW_UNSUPPORTED; // scanline too long
vga.config.scan_len = new_offset;
VGA_CheckScanLength();
break;
case 0x03: // get maximum scan line length
// the smaller of either the hardware maximum scanline length or
// the limit to get full y resolution of this mode
new_offset = S3_MAX_OFFSET;
if ((new_offset * bytes_per_offset * screen_height) > vmemsize)
new_offset = vmemsize / (bytes_per_offset * screen_height);
break;
default:
return VESA_UNIMPLEMENTED;
}
// set up the return values
bytes = (Bit16u)(new_offset * bytes_per_offset);
pixels = (Bit16u)(new_offset * pixels_per_offset);
if (!bytes)
// return failure on division by zero
// some real VESA BIOS implementations may crash here
return VESA_FAIL;
lines = (Bit16u)(vmemsize / bytes);
if (CurMode->type==M_TEXT)
lines *= CurMode->cheight;
return VESA_SUCCESS;
}
void vga_write_p3d5(Bitu port,Bitu val,Bitu iolen) {
// if((crtc(index)!=0xe)&&(crtc(index)!=0xf))
// LOG_MSG("CRTC w #%2x val %2x",crtc(index),val);
switch(crtc(index)) {
case 0x00: /* Horizontal Total Register */
if (crtc(read_only)) break;
crtc(horizontal_total)=val;
/* 0-7 Horizontal Total Character Clocks-5 */
break;
case 0x01: /* Horizontal Display End Register */
if (crtc(read_only)) break;
if (val != crtc(horizontal_display_end)) {
crtc(horizontal_display_end)=val;
VGA_StartResize();
}
/* 0-7 Number of Character Clocks Displayed -1 */
break;
case 0x02: /* Start Horizontal Blanking Register */
if (crtc(read_only)) break;
crtc(start_horizontal_blanking)=val;
/* 0-7 The count at which Horizontal Blanking starts */
break;
case 0x03: /* End Horizontal Blanking Register */
if (crtc(read_only)) break;
crtc(end_horizontal_blanking)=val;
/*
0-4 Horizontal Blanking ends when the last 6 bits of the character
counter equals this field. Bit 5 is at 3d4h index 5 bit 7.
5-6 Number of character clocks to delay start of display after Horizontal
Total has been reached.
7 Access to Vertical Retrace registers if set. If clear reads to 3d4h
index 10h and 11h access the Lightpen read back registers ??
*/
break;
case 0x04: /* Start Horizontal Retrace Register */
if (crtc(read_only)) break;
crtc(start_horizontal_retrace)=val;
/* 0-7 Horizontal Retrace starts when the Character Counter reaches this value. */
break;
case 0x05: /* End Horizontal Retrace Register */
if (crtc(read_only)) break;
crtc(end_horizontal_retrace)=val;
/*
0-4 Horizontal Retrace ends when the last 5 bits of the character counter
equals this value.
5-6 Number of character clocks to delay start of display after Horizontal
Retrace.
7 bit 5 of the End Horizontal Blanking count (See 3d4h index 3 bit 0-4)
*/
break;
case 0x06: /* Vertical Total Register */
if (crtc(read_only)) break;
if (val != crtc(vertical_total)) {
crtc(vertical_total)=val;
VGA_StartResize();
}
/* 0-7 Lower 8 bits of the Vertical Total. Bit 8 is found in 3d4h index 7
bit 0. Bit 9 is found in 3d4h index 7 bit 5.
Note: For the VGA this value is the number of scan lines in the display -2.
*/
break;
case 0x07: /* Overflow Register */
//Line compare bit ignores read only */
vga.config.line_compare=(vga.config.line_compare & 0x6ff) | (val & 0x10) << 4;
if (crtc(read_only)) break;
if ((vga.crtc.overflow ^ val) & 0xd6) {
crtc(overflow)=val;
VGA_StartResize();
} else crtc(overflow)=val;
/*
0 Bit 8 of Vertical Total (3d4h index 6)
1 Bit 8 of Vertical Display End (3d4h index 12h)
2 Bit 8 of Vertical Retrace Start (3d4h index 10h)
3 Bit 8 of Start Vertical Blanking (3d4h index 15h)
4 Bit 8 of Line Compare Register (3d4h index 18h)
5 Bit 9 of Vertical Total (3d4h index 6)
6 Bit 9 of Vertical Display End (3d4h index 12h)
7 Bit 9 of Vertical Retrace Start (3d4h index 10h)
*/
break;
case 0x08: /* Preset Row Scan Register */
crtc(preset_row_scan)=val;
vga.config.hlines_skip=val&31;
if (IS_VGA_ARCH) vga.config.bytes_skip=(val>>5)&3;
else vga.config.bytes_skip=0;
// LOG_DEBUG("Skip lines %d bytes %d",vga.config.hlines_skip,vga.config.bytes_skip);
/*
0-4 Number of lines we have scrolled down in the first character row.
Provides Smooth Vertical Scrolling.b
5-6 Number of bytes to skip at the start of scanline. Provides Smooth
Horizontal Scrolling together with the Horizontal Panning Register
(3C0h index 13h).
*/
break;
case 0x09: /* Maximum Scan Line Register */
{
if (IS_VGA_ARCH) {
vga.config.line_compare &= 0x5ff;
vga.config.line_compare |= (val&0x40)<<3;
} else if(machine==MCH_EGA) {
val &= 0x7f; // EGA ignores the doublescan bit
}
Bit8u old = crtc(maximum_scan_line);
crtc(maximum_scan_line) = val;
if(!vga.draw.doublescan_merging) {
if ((old ^ val) & 0x20) VGA_StartResize();
vga.draw.address_line_total = (val &0x1F) + 1;
if (val&0x80) vga.draw.address_line_total*=2;
} else if ((old ^ val) & 0xbf)
VGA_StartResize();
/*
0-4 Number of scan lines in a character row -1. In graphics modes this is
the number of times (-1) the line is displayed before passing on to
the next line (0: normal, 1: double, 2: triple...).
This is independent of bit 7, except in CGA modes which seems to
require this field to be 1 and bit 7 to be set to work.
5 Bit 9 of Start Vertical Blanking
6 Bit 9 of Line Compare Register
7 Doubles each scan line if set. I.e. displays 200 lines on a 400 display.
*/
break;
}
case 0x0A: /* Cursor Start Register */
crtc(cursor_start)=val;
vga.draw.cursor.sline=val&0x1f;
if (IS_VGA_ARCH) vga.draw.cursor.enabled=!(val&0x20);
else vga.draw.cursor.enabled=true;
/*
0-4 First scanline of cursor within character.
5 Turns Cursor off if set
*/
break;
case 0x0B: /* Cursor End Register */
crtc(cursor_end)=val;
vga.draw.cursor.eline=val&0x1f;
vga.draw.cursor.delay=(val>>5)&0x3;
/*
0-4 Last scanline of cursor within character
5-6 Delay of cursor data in character clocks.
*/
break;
case 0x0C: /* Start Address High Register */
crtc(start_address_high)=val;
vga.config.display_start=(vga.config.display_start & 0xFF00FF)| (val << 8);
/* 0-7 Upper 8 bits of the start address of the display buffer */
page_flip_debug_notify();
break;
case 0x0D: /* Start Address Low Register */
crtc(start_address_low)=val;
vga.config.display_start=(vga.config.display_start & 0xFFFF00)| val;
/* 0-7 Lower 8 bits of the start address of the display buffer */
page_flip_debug_notify();
break;
case 0x0E: /*Cursor Location High Register */
crtc(cursor_location_high)=val;
vga.config.cursor_start&=0xff00ff;
vga.config.cursor_start|=val << 8;
/* 0-7 Upper 8 bits of the address of the cursor */
break;
case 0x0F: /* Cursor Location Low Register */
//TODO update cursor on screen
crtc(cursor_location_low)=val;
vga.config.cursor_start&=0xffff00;
vga.config.cursor_start|=val;
/* 0-7 Lower 8 bits of the address of the cursor */
break;
case 0x10: /* Vertical Retrace Start Register */
crtc(vertical_retrace_start)=val;
/*
0-7 Lower 8 bits of Vertical Retrace Start. Vertical Retrace starts when
the line counter reaches this value. Bit 8 is found in 3d4h index 7
bit 2. Bit 9 is found in 3d4h index 7 bit 7.
*/
break;
case 0x11: /* Vertical Retrace End Register */
crtc(vertical_retrace_end)=val;
if (IS_EGAVGA_ARCH && !(val & 0x10)) {
vga.draw.vret_triggered=false;
if (GCC_UNLIKELY(machine==MCH_EGA)) PIC_DeActivateIRQ(9);
}
if (IS_VGA_ARCH) crtc(read_only)=(val & 128)>0;
else crtc(read_only)=false;
/*
0-3 Vertical Retrace ends when the last 4 bits of the line counter equals
this value.
4 if clear Clears pending Vertical Interrupts.
5 Vertical Interrupts (IRQ 2) disabled if set. Can usually be left
disabled, but some systems (including PS/2) require it to be enabled.
6 If set selects 5 refresh cycles per scanline rather than 3.
7 Disables writing to registers 0-7 if set 3d4h index 7 bit 4 is not
affected by this bit.
*/
break;
case 0x12: /* Vertical Display End Register */
if (val!=crtc(vertical_display_end)) {
if (abs((Bits)val-(Bits)crtc(vertical_display_end))<3) {
// delay small vde changes a bit to avoid screen resizing
// if they are reverted in a short timeframe
PIC_RemoveEvents(VGA_SetupDrawing);
vga.draw.resizing=false;
crtc(vertical_display_end)=val;
VGA_StartResize(150);
} else {
crtc(vertical_display_end)=val;
VGA_StartResize();
}
}
/*
0-7 Lower 8 bits of Vertical Display End. The display ends when the line
counter reaches this value. Bit 8 is found in 3d4h index 7 bit 1.
Bit 9 is found in 3d4h index 7 bit 6.
*/
break;
case 0x13: /* Offset register */
crtc(offset)=val;
vga.config.scan_len&=0x300;
vga.config.scan_len|=val;
VGA_CheckScanLength();
/*
0-7 Number of bytes in a scanline / K. Where K is 2 for byte mode, 4 for
word mode and 8 for Double Word mode.
*/
break;
case 0x14: /* Underline Location Register */
crtc(underline_location)=val;
if (IS_VGA_ARCH) {
//Byte,word,dword mode
if ( crtc(underline_location) & 0x40 )
vga.config.addr_shift = 2;
else if ( crtc( mode_control) & 0x40 )
vga.config.addr_shift = 0;
else
vga.config.addr_shift = 1;
} else {
vga.config.addr_shift = 1;
}
VGA_CheckScanLength();
/*
0-4 Position of underline within Character cell.
5 If set memory address is only changed every fourth character clock.
6 Double Word mode addressing if set
*/
break;
case 0x15: /* Start Vertical Blank Register */
if (val!=crtc(start_vertical_blanking)) {
crtc(start_vertical_blanking)=val;
VGA_StartResize();
}
/*
0-7 Lower 8 bits of Vertical Blank Start. Vertical blanking starts when
the line counter reaches this value. Bit 8 is found in 3d4h index 7
bit 3.
*/
break;
case 0x16: /* End Vertical Blank Register */
if (val!=crtc(end_vertical_blanking)) {
crtc(end_vertical_blanking)=val;
VGA_StartResize();
}
/*
0-6 Vertical blanking stops when the lower 7 bits of the line counter
equals this field. Some SVGA chips uses all 8 bits!
IBM actually says bits 0-7.
*/
break;
case 0x17: /* Mode Control Register */
crtc(mode_control)=val;
vga.tandy.line_mask = (~val) & 3;
//Byte,word,dword mode
if ( crtc(underline_location) & 0x40 )
vga.config.addr_shift = 2;
else if ( crtc( mode_control) & 0x40 )
vga.config.addr_shift = 0;
else
vga.config.addr_shift = 1;
if ( vga.tandy.line_mask ) {
vga.tandy.line_shift = 13;
vga.tandy.addr_mask = (1 << 13) - 1;
} else {
vga.tandy.addr_mask = ~0;
vga.tandy.line_shift = 0;
}
VGA_CheckScanLength();
//Should we really need to do a determinemode here?
// VGA_DetermineMode();
/*
0 If clear use CGA compatible memory addressing system
by substituting character row scan counter bit 0 for address bit 13,
thus creating 2 banks for even and odd scan lines.
1 If clear use Hercules compatible memory addressing system by
substituting character row scan counter bit 1 for address bit 14,
thus creating 4 banks.
2 If set increase scan line counter only every second line.
3 If set increase memory address counter only every other character clock.
5 When in Word Mode bit 15 is rotated to bit 0 if this bit is set else
bit 13 is rotated into bit 0.
6 If clear system is in word mode. Addresses are rotated 1 position up
bringing either bit 13 or 15 into bit 0.
7 Clearing this bit will reset the display system until the bit is set again.
*/
break;
case 0x18: /* Line Compare Register */
crtc(line_compare)=val;
vga.config.line_compare=(vga.config.line_compare & 0x700) | val;
/*
0-7 Lower 8 bits of the Line Compare. When the Line counter reaches this
value, the display address wraps to 0. Provides Split Screen
facilities. Bit 8 is found in 3d4h index 7 bit 4.
Bit 9 is found in 3d4h index 9 bit 6.
*/
break;
default:
if (svga.write_p3d5) {
svga.write_p3d5(crtc(index), val, iolen);
} else {
LOG(LOG_VGAMISC,LOG_NORMAL)("VGA:CRTC:Write to unknown index %X",crtc(index));
}
break;
}