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Split the VBE bank into separate read and write apertures. The compatibility

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mode sets both banks to the same value. Reading VBE bank register always
returns the write aperture setting. This feature is designed for the scrolling
function of the VBE 'write character' support. VBE code should use compatibility
mode for now.
TODO: update VGABIOS to use this feature.
This commit is contained in:
Volker Ruppert 2021-05-30 16:13:37 +00:00
parent c78c1a9af9
commit 733e466628
2 changed files with 27 additions and 11 deletions
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32
bochs/iodev/display/vga.cc
View File

@ -105,7 +105,8 @@ bool bx_vga_c::init_vga_extension(void)
BX_VGA_THIS vbe.xres=640;
BX_VGA_THIS vbe.yres=480;
BX_VGA_THIS vbe.bpp=8;
BX_VGA_THIS vbe.bank=0;
BX_VGA_THIS vbe.bank[0] = 0;
BX_VGA_THIS vbe.bank[1] = 0;
BX_VGA_THIS vbe.bank_granularity_kb=64;
BX_VGA_THIS vbe.curindex=0;
BX_VGA_THIS vbe.offset_x=0;
@ -188,7 +189,8 @@ void bx_vga_c::register_state(void)
new bx_shadow_num_c(vbe, "xres", &BX_VGA_THIS vbe.xres);
new bx_shadow_num_c(vbe, "yres", &BX_VGA_THIS vbe.yres);
new bx_shadow_num_c(vbe, "bpp", &BX_VGA_THIS vbe.bpp);
new bx_shadow_num_c(vbe, "bank", &BX_VGA_THIS vbe.bank);
new bx_shadow_num_c(vbe, "bank0", &BX_VGA_THIS vbe.bank[0]);
new bx_shadow_num_c(vbe, "bank1", &BX_VGA_THIS vbe.bank[1]);
new bx_shadow_num_c(vbe, "bank_granularity_kb", &BX_VGA_THIS vbe.bank_granularity_kb);
BXRS_PARAM_BOOL(vbe, enabled, BX_VGA_THIS vbe.enabled);
new bx_shadow_num_c(vbe, "curindex", &BX_VGA_THIS vbe.curindex);
@ -740,7 +742,7 @@ bx_vga_c::vbe_mem_read(bx_phy_address addr)
offset = (Bit32u)(addr - BX_VGA_THIS vbe.base_address);
} else if (addr < 0xB0000) {
// banked mode read
offset = (Bit32u)(BX_VGA_THIS vbe.bank * (BX_VGA_THIS vbe.bank_granularity_kb << 10) +
offset = (Bit32u)(BX_VGA_THIS vbe.bank[1] * (BX_VGA_THIS vbe.bank_granularity_kb << 10) +
(addr & 0xffff));
} else {
// out of bounds read
@ -765,7 +767,7 @@ bx_vga_c::vbe_mem_write(bx_phy_address addr, Bit8u value)
offset = (Bit32u)(addr - BX_VGA_THIS vbe.base_address);
} else if (addr < 0xB0000) {
// banked mode write
offset = (Bit32u)(BX_VGA_THIS vbe.bank * (BX_VGA_THIS vbe.bank_granularity_kb << 10) +
offset = (Bit32u)(BX_VGA_THIS vbe.bank[0] * (BX_VGA_THIS vbe.bank_granularity_kb << 10) +
(addr & 0xffff));
} else {
// ignore out of bounds write
@ -864,7 +866,7 @@ Bit32u bx_vga_c::vbe_read(Bit32u address, unsigned io_len)
if (BX_VGA_THIS vbe.get_capabilities) {
return (VBE_DISPI_BANK_GRANULARITY_32K << 8);
} else {
return BX_VGA_THIS vbe.bank;
return BX_VGA_THIS vbe.bank[0];
}
case VBE_DISPI_INDEX_X_OFFSET:
@ -1028,16 +1030,25 @@ Bit32u bx_vga_c::vbe_write(Bit32u address, Bit32u value, unsigned io_len)
case VBE_DISPI_INDEX_BANK: // set bank
{
Bit16u num_banks = (Bit16u)(VBE_DISPI_TOTAL_VIDEO_MEMORY_KB / BX_VGA_THIS vbe.bank_granularity_kb);
Bit16u rw_mode = VBE_DISPI_BANK_RW; // compatibility mode
if (BX_VGA_THIS vbe.bpp == VBE_DISPI_BPP_4) num_banks >>= 2;
if ((value & VBE_DISPI_BANK_RW) != 0) {
rw_mode = (value & VBE_DISPI_BANK_RW);
}
value &= 0x1ff;
// check for max bank nr
if (value < num_banks) {
BX_DEBUG(("VBE set bank to %d", value));
BX_VGA_THIS vbe.bank = value;
if ((rw_mode & VBE_DISPI_BANK_WR) != 0) {
BX_VGA_THIS vbe.bank[0] = value;
}
if ((rw_mode & VBE_DISPI_BANK_RD) != 0) {
BX_VGA_THIS vbe.bank[1] = value;
}
if (BX_VGA_THIS vbe.bank_granularity_kb == 64) {
BX_VGA_THIS s.plane_offset = (BX_VGA_THIS vbe.bank << 16);
BX_VGA_THIS s.plane_offset = (BX_VGA_THIS vbe.bank[0] << 16);
} else {
BX_VGA_THIS s.plane_offset = (BX_VGA_THIS vbe.bank << 15);
BX_VGA_THIS s.plane_offset = (BX_VGA_THIS vbe.bank[0] << 15);
}
} else {
BX_ERROR(("VBE set invalid bank (%d)", value));
@ -1111,7 +1122,7 @@ Bit32u bx_vga_c::vbe_write(Bit32u address, Bit32u value, unsigned io_len)
BX_VGA_THIS s.last_fh = 0;
} else {
BX_VGA_THIS s.plane_shift = VBE_DISPI_4BPP_PLANE_SHIFT;
BX_VGA_THIS s.plane_offset = (BX_VGA_THIS vbe.bank << 16);
BX_VGA_THIS s.plane_offset = (BX_VGA_THIS vbe.bank[0] << 16);
}
} else if (((value & VBE_DISPI_ENABLED) == 0) && BX_VGA_THIS vbe.enabled) {
BX_INFO(("VBE disabling"));
@ -1139,7 +1150,8 @@ Bit32u bx_vga_c::vbe_write(Bit32u address, Bit32u value, unsigned io_len)
}
if (new_bank_gran != BX_VGA_THIS vbe.bank_granularity_kb) {
BX_VGA_THIS vbe.bank_granularity_kb = new_bank_gran;
BX_VGA_THIS vbe.bank = 0;
BX_VGA_THIS vbe.bank[0] = 0;
BX_VGA_THIS vbe.bank[1] = 0;
BX_VGA_THIS s.plane_offset = 0;
}
new_vbe_8bit_dac = ((value & VBE_DISPI_8BIT_DAC) != 0);

6
bochs/iodev/display/vga.h
View File

@ -73,6 +73,10 @@
#define VBE_DISPI_LFB_ENABLED 0x40
#define VBE_DISPI_NOCLEARMEM 0x80
#define VBE_DISPI_BANK_WR 0x4000
#define VBE_DISPI_BANK_RD 0x8000
#define VBE_DISPI_BANK_RW 0xc000
#define VBE_DISPI_LFB_PHYSICAL_ADDRESS 0xE0000000
#define VBE_DISPI_TOTAL_VIDEO_MEMORY_KB (VBE_DISPI_TOTAL_VIDEO_MEMORY_MB * 1024)
@ -147,7 +151,7 @@ private:
Bit16u max_xres;
Bit16u max_yres;
Bit16u max_bpp;
Bit16u bank;
Bit16u bank[2];
Bit16u bank_granularity_kb;
bool enabled;
Bit16u curindex;