94 lines
1.9 KiB
NASM
94 lines
1.9 KiB
NASM
; disk booting routines
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; load the boot sector of disk 0 to 0x00000800 and jump to it
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; inputs:
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; none
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; outputs:
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; none (returns if disk 0 is not bootable)
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start_boot_process:
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; read sector 0 to 0x800
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mov r0, 0
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mov r1, 0
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mov r2, 0x00000800
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call read_sector
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; check for the bootable magic bytes
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cmp [0x000009FC], 0x523C334C
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ifnz ret
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; now clean up and jump to the loaded binary
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call boot_cleanup
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mov rsp, SYSTEM_STACK ; reset stack pointer
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mov r0, 0 ; booting from disk id 0
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jmp 0x00000800
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; load the boot sector of the romdisk and jump to it
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; inputs:
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; none
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; outputs:
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; none (returns if romdisk is not bootable)
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start_boot_process_from_romdisk:
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; read sector 0 to 0x800
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mov r0, 0
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mov r1, 4
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mov r2, 0x00000800
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call read_sector
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; check for the bootable magic bytes
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cmp [0x000009FC], 0x523C334C
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ifnz ret
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; now clean up and jump to the loaded binary
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call boot_cleanup
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mov rsp, SYSTEM_STACK ; reset stack pointer
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mov r0, 4 ; booting from disk id 4
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jmp 0x00000800
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; clean up the system's state before jumping to the loaded binary
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; inputs:
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; none
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; outputs:
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; none
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boot_cleanup:
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; clear the background
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mov r0, BACKGROUND_COLOR
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call fill_background
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; disable the blinking disk icon
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call cleanup_icon
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movz.8 r0, 0
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movz.8 r1, 0
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movz.8 r2, 0
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movz.8 r3, 0
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movz.8 r4, 0
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movz.8 r5, 0
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movz.8 r6, 0
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movz.8 r7, 0
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movz.8 r8, 0
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movz.8 r9, 0
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movz.8 r10, 0
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movz.8 r11, 0
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movz.8 r12, 0
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movz.8 r13, 0
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movz.8 r14, 0
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movz.8 r15, 0
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movz.8 r16, 0
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movz.8 r17, 0
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movz.8 r18, 0
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movz.8 r19, 0
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movz.8 r20, 0
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movz.8 r21, 0
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movz.8 r22, 0
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movz.8 r23, 0
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movz.8 r24, 0
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movz.8 r25, 0
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movz.8 r26, 0
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movz.8 r27, 0
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movz.8 r28, 0
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movz.8 r29, 0
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movz.8 r30, 0
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movz.8 r31, 0
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ret
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