A TempleOS distro for heretics
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5.5 KiB

asm {/* See $LK,"::/Doc/Boot.DD"$.
TempleOS starts in real, calls some BIOS
routines, switches to 32 bit, and 64 bit mode
and continues in $LK,"HolyC",A="FI:::/Doc/HolyC.DD"$ at $LK,"KMain",A="MN:KMain"$().
The boot loader jumps here in real-mode (16-bit).
It actually jumps to the $LK,"CBinFile",A="MN:CBinFile"$ header which is
placed just before this by $LK,"the compiler",A="FF:::/Compiler/CMain.HC,16 ALIGN"$.
The header begins with a short jmp to
the start of this file's code which begins
with the following small jump past some data.
This file is first in the Kernel image
because it is #included first. $LK,"Kernel.PRJ",A="FF:::/Kernel/Kernel.PRJ,KStart16:1"$
*/
USE16
SYS_KERNEL:: //This must match $LK,"CKernel",A="MN:CKernel"$.
JMP I16 CORE0_16BIT_INIT
//************************************
// ASM Global vars required for 16-bit start-up
ALIGN 4,OC_NOP
SYS_BOOT_SRC:: DU32 BOOT_SRC_NULL;
SYS_BOOT_BLK:: DU32 0;
SYS_BOOT_PATCH_TABLE_BASE:: DU32 0;
SYS_RUN_LEVEL:: DU32 0;
#exe {StreamPrint("SYS_COMPILE_TIME:: DU64 0x%X;",Now);} //See $LK,"BootDVDProbe",A="MN:BootDVDProbe"$
#assert SYS_COMPILE_TIME+sizeof(CDate)+sizeof(CBinFile)<DVD_BLK_SIZE
MEM_BOOT_BASE:: DU32 0; //Offset from start used by reboot
MEM_E801:: DU16 0,0;
MEM_E820:: DU8 MEM_E820_ENTRIES_NUM*sizeof(CMemE820) DUP (0);
MEM_PHYSICAL_SPACE:: DU64 0;
SYS_GDT_PTR:: DU16 sizeof(CGDT)-1;
DU64 0;
SYS_PCI_BUSES:: DU16 0;
ALIGN 16,OC_NOP
SYS_GDT:: //See $LK,"CGDT",A="MN:CGDT"$
GDT_NULL: DU64 0,0;
GDT_BOOT_DS: DU64 0x00CF92000000FFFF,0; //Gets patched.
GDT_BOOT_CS: DU64 0x00CF9A000000FFFF,0; //Gets patched.
GDT_CS32: DU64 0x00CF9A000000FFFF,0;
GDT_CS64: DU64 0x00209A0000000000,0; //The $LK,"Charter",A="FI:::/Doc/Charter.DD"$ says just ring0.
GDT_CS64_RING3: DU64 0x0020FA0000000000,0; //$LK,"Ring3",A="FI:::/Demo/Lectures/Ring3.HC"$, so you can play with.
GDT_DS: DU64 0x00CF92000000FFFF,0;
GDT_DS_RING3: DU64 0x00CFF2000000FFFF,0;
GDT_TR: DU8 MP_PROCESSORS_NUM*16 DUP(0);
GDT_TR_RING3: DU8 MP_PROCESSORS_NUM*16 DUP(0);
#assert $$-SYS_GDT==sizeof(CGDT)
#assert $$-SYS_KERNEL==sizeof(CKernel)-sizeof(CBinFile)
//************************************
CORE0_16BIT_INIT::
//EAX is $LK,"SYS_BOOT_SRC",A="FF:::/Kernel/KStart16.HC,[SYS_BOOT_SRC]"$. (Val passed from boot blk, $LK,"BootHD",A="FF:::/Adam/Opt/Boot/BootHD.HC,BOOT_SRC_HARDDRV"$, $LK,"BootDVD",A="FF:::/Adam/Opt/Boot/BootDVD.HC,BOOT_SRC_DVD"$, & $LK,"BootRAM",A="FF:::/Adam/Opt/Boot/BootRAM.HC,BOOT_SRC_RAM"$.)
MOV ECX,EAX
MOV AX,(BOOT_RAM_LIMIT-BOOT_STK_SIZE)/16
MOV SS,AX
MOV SP,BOOT_STK_SIZE
PUSH ECX //Will be $LK,"SYS_BOOT_SRC",A="FF:::/Kernel/KStart16.HC,[SYS_BOOT_SRC]"$. See $LK,"BootHD",A="FF:::/Adam/Opt/Boot/BootHD.HC,BOOT_SRC_HARDDRV"$, $LK,"BootDVD",A="FF:::/Adam/Opt/Boot/BootDVD.HC,BOOT_SRC_DVD"$ & $LK,"BootRAM",A="FF:::/Adam/Opt/Boot/BootRAM.HC,BOOT_SRC_RAM"$.
PUSH EBX
CALL U16 GET_RIP
GET_RIP: POP BX
SUB BX,GET_RIP
SHR BX,4
MOV AX,CS
ADD AX,BX
PUSH AX
PUSH U16 @@05
RETF
@@05: STI
MOV AX,CS
MOV DS,AX
MOV U32 [SYS_RUN_LEVEL],RLF_16BIT
MOV AX,0x4F02
MOV BX,0x12 //640x480 16 color
#exe {
if (!kernel_cfg->opts[CFG_TEXT_MODE])
StreamPrint("INT 0x10"); //Enable VGA
};
CMP AX,0x004F
JNE @@10 //Jmp if fail
BTS U32 [SYS_RUN_LEVEL],RLf_VGA
@@10:
//Get mem maps.
MOV AX,0xE801
INT 0x15
MOV U16 [MEM_E801],CX
MOV U16 [MEM_E801+2],DX
MOV CX,MEM_E820_ENTRIES_NUM-1 //Leave one to terminate
XOR EBX,EBX
MOV AX,DS
MOV ES,AX
MOV DI,MEM_E820
@@15: PUSH CX
MOV EAX,0xE820
MOV ECX,sizeof(CMemE820)
MOV EDX,'PAMS'
INT 0x15
JC @@20
CMP EAX,'PAMS'
JNE @@20
TEST EBX,EBX
JZ @@20
ADD DI,sizeof(CMemE820)
POP CX
LOOP @@15
SUB SP,2
@@20: ADD SP,2
//Find how much space to map, start with E801 limit.
XOR EAX,EAX
MOV AX,[MEM_E801+2]
SHL EAX,16
ADD EAX,SYS_16MEG_AREA_LIMIT
XOR EDX,EDX
//Find max of E820 to set mapped space.
MOV SI,MEM_E820
@@25: MOV CL,CMemE820.type[SI]
TEST CL,CL
JZ @@35
MOV EBX,CMemE820.base[SI]
MOV ECX,CMemE820.base+4[SI]
ADD EBX,CMemE820.len[SI]
ADC ECX,CMemE820.len+4[SI]
SUB EBX,EAX
SBB ECX,EDX
JC @@30
MOV EAX,CMemE820.base[SI]
MOV EDX,CMemE820.base+4[SI]
ADD EAX,CMemE820.len[SI]
ADC EDX,CMemE820.len+4[SI]
@@30: ADD SI,sizeof(CMemE820)
JMP @@25
@@35: MOV [MEM_PHYSICAL_SPACE],EAX
MOV [MEM_PHYSICAL_SPACE+4],EDX
//Get PCI Bus Info
MOV U16 [SYS_PCI_BUSES],256
XOR DX,DX
MOV AX,0xB101
INT 0x1A
CMP DX,'PC'
JNE @@40
MOV CH,0
INC CX
MOV U16 [SYS_PCI_BUSES],CX
@@40:
CLI
//Enable A20
IN AL,0x92
OR AL,2
OUT 0x92,AL
POP U32 [SYS_BOOT_BLK]
POP U32 [SYS_BOOT_SRC] //See $LK,"BootHD",A="FF:::/Adam/Opt/Boot/BootHD.HC,BOOT_SRC_HARDDRV"$, $LK,"BootDVD",A="FF:::/Adam/Opt/Boot/BootDVD.HC,BOOT_SRC_DVD"$, & $LK,"BootRAM",A="FF:::/Adam/Opt/Boot/BootRAM.HC,BOOT_SRC_RAM"$.
CLD
XOR EAX,EAX
MOV AX,CS
MOV DS,AX
MOV ES,AX
SHL EAX,4
MOV U32 [MEM_BOOT_BASE],EAX
MOV DX,CS
SUB DX,sizeof(CBinFile)/16
#assert !(sizeof(CBinFile)&15)
MOV GS,DX
MOV EDX,EAX
ADD EDX,U32 GS:[CBinFile.patch_table_offset]
SUB EDX,sizeof(CBinFile)
MOV U32 [SYS_BOOT_PATCH_TABLE_BASE],EDX
ADD U32 [GDT_BOOT_DS+2],EAX
ADD U32 [GDT_BOOT_CS+2],EAX
ADD EAX,I32 SYS_GDT
MOV U32 [SYS_GDT_PTR+CSysLimitBase.base],EAX
LGDT U32 [SYS_GDT_PTR]
MOV EAX,SYS_START_CR0
MOV_CR0_EAX
/* The assembler doesn't support far jumps so
we hand code it. 16-bit code is not important
enough to fully implement in the assembler.
To complete the switch to 32-bit mode, we have to load
the code segment with a far jump.
*/
DU8 0x66,0xEA; //JMP CGDT.boot_cs:CORE0_32BIT_INIT
DU32 CORE0_32BIT_INIT;
DU16 CGDT.boot_cs;
#assert $$+16<=0xFFFF
}