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227 lines
3.7 KiB
227 lines
3.7 KiB
#generate 16-bit code |
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.code16 |
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#hint the assembler that here is the executable code located |
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.text |
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.globl _start; |
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#boot code entry |
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_start: |
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jmp _boot |
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start: .asciz "Start.\n\r" |
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error: .asciz "Error.\n\r" |
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succes: .asciz "Succes.\n\r" |
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ffs: .asciz "F.\n\r" |
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end: .asciz "End.\n\r" |
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derpy2str: .asciz "This is from derpy2.\n\r" |
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cookies: .word derpy2 |
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.macro mWriteString str #macro which calls a function to print a string |
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leaw \str, %si |
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call .writeStringIn |
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.endm |
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# function to print the string |
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.writeStringIn: |
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lodsb |
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orb %al, %al |
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jz .writeStringOut |
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movb $0x0e, %ah |
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int $0x10 |
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jmp .writeStringIn |
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.writeStringOut: |
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ret |
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_boot: |
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mWriteString start |
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movb $0x0e, %ah |
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movb $'X', %al |
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int $0x10 |
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movb $'\n', %al |
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int $0x10 |
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movb $'\r', %al |
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int $0x10 |
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lgdt gdtdesc |
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#movb $42, %bl #NOT 'A' |
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#movb %bl, 0x512 |
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#This goes first as to now overwrite %ah and %al. |
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mov $0x00, %ax |
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#mov $0x08, %ax |
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mov %ax, %es #Section to write into |
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mov $0x02, %ah # Read sectors from drive |
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mov $0x01, %al # Number of sectors to read |
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mov $0x00, %ch # Low 8 bits of cylinder |
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mov $0x02, %cl # First sector to read (bits 0-5), upper bits of cylinder (bits 6-7) |
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mov $0x00, %dh # Head number |
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mov $0x00, %dl # Drive number |
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# mov $0x00, %es |
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#mov $0x7e00, %bx #Offset into section |
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mov $(_start+0x200), %bx #Offset into section |
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#mov $0x0, %bx #Offset into section |
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int $0x13 # Low level disk services |
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jnc notcarry |
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#mWriteString error |
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jmp endcarrycheck |
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notcarry: |
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#mWriteString succes |
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#mov $0x7000, %ax |
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#movb (%ax), %bl |
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#movb %bl, ffs |
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#movb 0x7000, %bl |
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#movb %bl, ffs |
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#mWriteString ffs |
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#fallthrough |
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endcarrycheck: |
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#mWriteString mystr-block2_offset |
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#mWriteString 0x513 |
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#mWriteString mystr |
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#ljmp $0x0, $derpy |
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#.byte 0, 0, 0, 0, 0, 0, 0, 0 |
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#ljmp $0x00, $0x7e00 |
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#ljmp $0x00, $derpy2 |
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ljmp $0x00, $code |
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# movw $derpy, %ax |
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# |
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# cmp $0x7e00, %ax |
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# je equal |
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# mWriteString error |
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# jmp after |
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# |
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# equal: |
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# mWriteString succes |
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# |
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# after: |
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/* |
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movb $0x0e, %ah |
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movw $derpy, %cx |
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movb 0x0e, %ah |
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movb $'I', %al |
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int $0x10 |
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movb 0x0e, %ah |
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movb $'J', %al |
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int $0x10 |
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*/ |
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#movw $0x7E00, %cx |
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movw $derpy2, %cx |
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movb $0x0e, %ah |
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#movb $'Y', %al |
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movb %ch, %al |
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#movb $'H', %al |
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#movb $0x7E, %al |
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int $0x10 |
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movb $0x0e, %ah |
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#movb $'Z', %al |
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movb %cl, %al |
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#add $0x7E, %al |
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#sub $0x50, %al |
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#movb $0x3C, %al |
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int $0x10 |
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movb $0x0e, %ah |
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movb $'\n', %al |
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int $0x10 |
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movb $0x0e, %ah |
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movb $'\r', %al |
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int $0x10 |
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#mWriteString mystr |
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#jmp derpy |
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derpyret: |
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mWriteString end |
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#jmp 0x7008 |
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#endend: |
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#mWriteString end |
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cli |
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hlt |
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# |
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derpy: |
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mWriteString ffs |
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ljmp $0x00, $derpyret |
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#jmp derpyret |
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.p2align 2 /* force 4-byte alignment */ |
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gdt: |
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.word 0, 0 |
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.byte 0, 0, 0, 0 |
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/* code segment */ |
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.word 0xFFFF, 0 |
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.byte 0, 0x9A, 0xCF, 0 |
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/* data segment */ |
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.word 0xFFFF, 0 |
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.byte 0, 0x92, 0xCF, 0 |
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/* 16 bit real mode CS */ |
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.word 0xFFFF, 0 |
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.byte 0, 0x9E, 0, 0 |
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/* 16 bit real mode DS */ |
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.word 0xFFFF, 0 |
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.byte 0, 0x92, 0, 0 |
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/* this is the GDT descriptor */ |
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gdtdesc: |
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.word 0x27 /* limit */ |
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.long gdt /* addr */ |
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#move to 510th byte from the start and append boot signature |
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. = _start + 510 |
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.byte 0x55 |
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.byte 0xaa |
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#block2_offset: |
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.byte 'A' #Byte 513 |
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#mystr: .asciz "asdf\n\r" |
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#derpderp: |
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# mwriteString 0x7001 |
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# jmp endend |
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derpy2: |
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mWriteString derpy2str |
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ljmp $0x00, $derpyret |
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code: |
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mWriteString derpy2str |
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movb $0x0e, %ah |
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movb $'C', %al |
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int $0x10 |
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movb $0x0e, %ah |
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movb $'\n', %al |
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int $0x10 |
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movb $0x0e, %ah |
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movb $'\r', %al |
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int $0x10 |
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ljmp $0x00, $derpyret |
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. = _start + 1021 |
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.byte 0x00 |
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.word derpy2
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