6b0caea84c
By doing this we don't need to call bios functions, we can just jsr directly to the addresses. This does mean that everytime the bios changes the bootloader has to change, but ideally all the bootloader does is load the bios and then get remapped out of memory. Any important drivers like file system can be loaded from the bootloader. This also means that the runtime functions are located in the bios for the bootloader, so the rom will have to stay mapped in until the kernel is started, at which point it will have its own runtime and the rom and bootloader are no longer needed.
42 lines
513 B
ArmAsm
42 lines
513 B
ArmAsm
.importzp sp, ptr1, ptr2, ptr3, ptr4, tmp1, tmp2, tmp3
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.autoimport on
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.feature string_escapes
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.MACPACK generic
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_console_clear = $0
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_console_read_char = $2
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_console_write_char = $4
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_sd_readblock = $6
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.segment "BOOTSECTOR"
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_start:
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jmp _main
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.byte "SUPR6502"
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_main:
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lda #<str
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ldx #>str
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jsr _cputs
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@end: bra @end
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str: .asciiz "Hello from the bootloader!\r\n"
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_end:
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.res (446+_start-_end)
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.res 16
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.res 16
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.res 16
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.res 16
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.byte $55
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.byte $AA
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