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https://opencores.org/ocsvn/eco32/eco32/trunk
Subversion Repositories eco32
[/] [eco32/] [trunk/] [simtest/] [disk/] [mkmbr/] [mbr.s] - Rev 128
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; ; mbr.s -- the master boot record ; ; $8 I/O base address ; $9 temporary value ; $10 character ; $11 pointer to string ; $29 stack pointer ; $31 return address .set tba,0xF0300000 ; terminal base address start: sub $29,$29,4 ; save return register stw $31,$29,0 add $8,$0,tba ; set I/O base address add $11,$0,msg ; pointer to string loop: ldbu $10,$11,0 ; get char beq $10,$0,stop ; null - finished jal out ; output char add $11,$11,1 ; bump pointer j loop ; next char stop: ldw $31,$29,0 ; restore return register add $29,$29,4 jr $31 ; return out: ldw $9,$8,8 ; get status and $9,$9,1 ; xmtr ready? beq $9,$0,out ; no - wait stw $10,$8,12 ; send char jr $31 ; return msg: .byte 0x0D, 0x0A .byte "Error: This is the default MBR, " .byte "which cannot load anything." .byte 0x0D, 0x0A .byte "Please replace the disk, or " .byte "write an operating system onto it." .byte 0x0D, 0x0A .byte 0x0D, 0x0A, 0 .locate 512-2 sign: .byte 0x55, 0xAA
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