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boot.nas
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; cherryOS boot asm
; TAB=4
[INSTRSET "i486p"]
VBEMODE EQU 0x105 ; default 1024 x 768 x 8bit
; 0x100 : 640 x 400 x 8bit
; 0x101 : 640 x 480 x 8bit
; 0x103 : 800 x 600 x 8bit
; 0x105 : 1024 x 768 x 8bit
; 0x107 : 1280 x 1024 x 8bit
BOOTER EQU 0x00280000 ; load kernel
DSKCAC EQU 0x00100000 ; disk location
DSKCAC0 EQU 0x00008000
; BOOT_INFOÏà¹Ø
CYLS EQU 0x0ff0 ;set boot cyls
LEDS EQU 0x0ff1 ;led
VMODE EQU 0x0ff2
SCRNX EQU 0x0ff4 ;x
SCRNY EQU 0x0ff6 ;y
VRAM EQU 0x0ff8 ;vram
ORG 0xc200 ;mem location
; VBE
MOV AX,0x9000
MOV ES,AX
MOV DI,0
MOV AX,0x4f00
INT 0x10
CMP AX,0x004f
JNE scrn320
; VBE version
MOV AX,[ES:DI+4]
CMP AX,0x0200
JB scrn320 ; if (AX < 0x0200) goto scrn320
; screen
MOV CX,VBEMODE
MOV AX,0x4f01
INT 0x10
CMP AX,0x004f
JNE scrn320
CMP BYTE [ES:DI+0x19],8
JNE scrn320
CMP BYTE [ES:DI+0x1b],4
JNE scrn320
MOV AX,[ES:DI+0x00]
AND AX,0x0080
JZ scrn320 ;drop
; change
MOV BX,VBEMODE+0x4000
MOV AX,0x4f02
INT 0x10
MOV BYTE [VMODE],8
MOV AX,[ES:DI+0x12]
MOV [SCRNX],AX
MOV AX,[ES:DI+0x14]
MOV [SCRNY],AX
MOV EAX,[ES:DI+0x28]
MOV [VRAM],EAX
JMP led_status
scrn320:
MOV AL,0x13
MOV AH,0x00
INT 0x10
MOV BYTE [VMODE],8
MOV WORD [SCRNX],320
MOV WORD [SCRNY],200
MOV DWORD [VRAM],0x000a0000
;get led from BIOS
led_status:
MOV AH,0x02
INT 0x16 ; keyboard BIOS
MOV [LEDS],AL
MOV AL,0xff
OUT 0x21,AL
NOP
OUT 0xa1,AL
CLI
;set A20GATE
CALL waitkbdout
MOV AL,0xd1 ;#define KEYCMD_WRITE_OUTPORT 0xd1
OUT 0x64,AL ;io_out8(PORT_KEYCMD, KEYCMD_WRITE_OUTPORT)
CALL waitkbdout ;wait_KBC_sendready()
MOV AL,0xdf ; enable A20 ;#define KBC_OUTPORT_A20G_ENABLE 0xdf
OUT 0x60,AL ;io_out8(PORT_KEYDAT, KBC_OUTPORT_A20G_ENABLE)
CALL waitkbdout ;wait_KBC_sendready()
; virtual mode
LGDT [GDTR0] ; set tmp GDT
MOV EAX,CR0
AND EAX,0x7fffffff
OR EAX,0x00000001
MOV CR0,EAX
JMP pipelineflush
pipelineflush:
MOV AX,1*8
MOV DS,AX
MOV ES,AX
MOV FS,AX
MOV GS,AX
MOV SS,AX
; kernel copy
MOV ESI,kernel
MOV EDI,BOOTER
MOV ECX,512*1024/4
CALL memcpy
MOV ESI,0x7c00 ;src
MOV EDI,DSKCAC ;dst
MOV ECX,512/4
CALL memcpy
;remain
MOV ESI,DSKCAC0+512 ;src
MOV EDI,DSKCAC+512 ;dst
MOV ECX,0
MOV CL,BYTE [CYLS]
IMUL ECX,512*18*2/4
SUB ECX,512/4
CALL memcpy
; kernel begin
MOV EBX,BOOTER
MOV ECX,[EBX+16]
ADD ECX,3 ; ECX += 3;
SHR ECX,2 ; ECX /= 4;
JZ skip
MOV ESI,[EBX+20] ;src
ADD ESI,EBX
MOV EDI,[EBX+12] ;dst
CALL memcpy
skip:
MOV ESP,[EBX+12]
JMP DWORD 2*8:0x0000001b
waitkbdout:
IN AL,0x64
AND AL,0x02
IN AL,0x60
JNZ waitkbdout
RET
memcpy:
MOV EAX,[ESI]
ADD ESI,4
MOV [EDI],EAX
ADD EDI,4
SUB ECX,1
JNZ memcpy
RET
; memcpy
ALIGNB 16
GDT0:
RESB 8 ; NULL selector
DW 0xffff,0x0000,0x9200,0x00cf
DW 0xffff,0x0000,0x9a28,0x0047
DW 0
GDTR0:
DW 8*3-1
DD GDT0
ALIGNB 16
kernel: