92 lines
1.5 KiB
ArmAsm
92 lines
1.5 KiB
ArmAsm
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.code16
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main:
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/* fix up code seg */
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ljmp $0x0,$entry
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entry:
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/* init data segments */
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xor %ax, %ax
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mov %ax, %ds
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mov %ax, %ss
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/* save boot disk */
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mov %dl, boot_disk
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/* set up stack */
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mov $0x7b00, %ax
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mov %ax, %sp
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/* figure out sector size */
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mov $0x48, %ah
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mov boot_disk, %dl
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mov $drive_params, %si
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int $0x13
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/* figure out first sector of stage 2 */
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mov $0, %edx
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mov $BOOT_FILE_OFFSET, %eax
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mov (drive_params_bps), %ecx
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div %ecx
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mov %eax, dap_lba_low
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mov $BOOT_FILE_SIZE, %eax
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div %ecx
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inc %eax
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mov %ax, dap_sectors
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movl $0x7e00, dap_buffer
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mov $0x42, %ah /* Extended read */
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mov boot_disk, %dl /* Using our boot disk */
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mov $dap, %si /* From the DAP below */
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int $0x13
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mov $0, %ax
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mov %ax, %es
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mov %ax, %ds
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/* Now move the rest of our code somewhere low */
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mov $mover, %esi
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mov $0x7b00, %edi
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mov $(mover_end-mover), %ecx
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rep movsb
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mov $0x7b00, %eax
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jmp *%eax
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mover:
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mov $0x7e00, %esi
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mov $0x7c00, %edi
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mov $BOOT_FILE_SIZE, %ecx
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rep movsb
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mov $0x7c00, %eax
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jmp *%eax
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mover_end:
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boot_disk:
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.byte 0
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.align 4
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.global dap
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dap:
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.byte 16
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.byte 0 /* always 0 */
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.global dap_sectors
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dap_sectors:
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.word 1
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.global dap_buffer
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dap_buffer:
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.long 0x0
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.global dap_lba_low
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dap_lba_low:
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.long 0
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.global dap_lba_high
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dap_lba_high:
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.long 0
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.align 4
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drive_params:
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.word 0x1A
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.word 0 /* flags */
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.long 0 /* cylinders */
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.long 0 /* heads */
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.long 0 /* sectors */
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.quad 0 /* total sectors */
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drive_params_bps:
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.word 0 /* bytes per sector */
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.org 510
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.byte 0x55
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.byte 0xaa
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