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From: Luigi R. <ri...@ac...> - 2001-02-18 04:25:53
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> On 2/17/2001 10:17 PM Luigi Rizzo ri...@ac... wrote: > >While i have your attention -- how much work do you think it is > >necessary to remove the dependency on nasm and let the code compile > >just using the standard assembler (as i believe ?) which comes with > >FreeBSD/Linux/cygnus tools for windows ? > >Is it just a matter of replacing the .S files with equivalent ones > >in gcc syntax in case hey are not yet ? > > It's funny you should mention that. Someone recently contributed > translations that do this. I think we would certainly like to get rid of > the remaining dependencies on NASM/AS86, and I imagine the translation > will be aided by having an example. So my guess is that we're close to > this goal. ok so here is my contribution for comload.s ... cheers luigi # as comload.s -o comload.o # ld -Ttext 0 -o comload.out comload.o # objcopy -S -O binary comload.out comload .text .globl _start .code16 # Cheat a little with the relocations: .COM files are loaded at 0x100 _start: pushw %cs # generate return address movw $retaddr + 0x100, %ax pushw %ax # Intel didn''t specify an indirect far call that loads the address from # a near operand - it seems like nobody does computed far calls. So do it # the ugly way - dump it on the stack and "return" to the destination. movw %cs, %ax # calculate start address of loader movw $_body + 0x100, %bx movb $4, %cl shrw %cl, %bx addw %bx, %ax pushw %ax # new code segment movw $6, %ax pushw %ax # new offset lret retaddr: int $0x19 # should never reach this .align 16, 0 _body: |
