64 lines
1.2 KiB
NASM
64 lines
1.2 KiB
NASM
# OwOS
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# Copyright Benjamin Kyd (c) 2019
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# declare constants for the multiboot header
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.set ALIGN, 1<<0 # align loaded modules on page boundaries
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.set MEMINFO, 1<<1 # provide memory map
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.set FLAGS, ALIGN | MEMINFO # this is the Multiboot 'flag' field
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.set MAGIC, 0x1BADB002 #'magic number' lets bootloader find the header
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.set CHECKSUM, -(MAGIC + FLAGS) # checksum of above, to prove we are multiboot
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.section .multiboot
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.align 4
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.long MAGIC
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.long FLAGS
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.long CHECKSUM
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.section .bss
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.align 16
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stack_bottom:
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.skip 16384 # 16 KiB
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stack_top:
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.section .text
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.global _start
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.type _start, @function
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_start:
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# Settup stack
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mov $stack_top, %esp
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push %ebx
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push %eax
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call kernel_main
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cli
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1: hlt
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jmp 1b
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.global FPU_Init
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.type FPU_Init, @function
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FPU_Init:
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# FPU Config
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VAL_037F:
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.hword 0x037F
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VAL_037E:
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.hword 0x037E
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VAL_037A:
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.hword 0x037A
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# Configure FPU
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cli
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mov %cr0, %ecx
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or $0b00110010, %ecx
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and $0xFFFFFFFB, %ecx
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mov %ecx, %cr0
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fldcw VAL_037F
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fldcw VAL_037E
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fldcw VAL_037A
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fninit
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ret
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.size _start, . - _start
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