jhb 2006-09-28 19:38:02 UTC FreeBSD src repository
Modified files: sys/boot/i386/btx/btx btx.S Log: Optimize the int 15/87 handler for space to shave another 16 bytes off of BTX (and thus boot2): - Don't bother saving %eax, %ebx, or %ecx as it is not necessary. - Use a more compact sequence to load the base value out of a GDT entry by loading the contiguous low 24 bits into the upper 24 bits of %eax, loading the high 8 bits into %al, and using a ror to rotate the bits (2 mov's and a ror) rather than loading the pieces in smaller chunks (3 mov's and a shl). - Use movzwl + leal instead of movl + movw + shll + addl. - Use 'xchgl %eax,%foo' rather than 'movl %eax,%foo' for cases where it's ok to trash %eax. xchgl %eax, foo is a 1-byte opcode whereas the mov is a 2-byte opcode. - Use movzwl rather than xorl + movw. MFC after: 1 week Revision Changes Path 1.41 +17 -31 src/sys/boot/i386/btx/btx/btx.S _______________________________________________ cvs-all@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/cvs-all To unsubscribe, send any mail to "[EMAIL PROTECTED]"