/ This file encapsulates a tentative change made to deal with potential / motherboard problems with use of the REP instruction prefix in conjunction / with the x86 I/O instructions; due to PC bus timing problems, some / peripheral boards may be unable to supply data within the required bus / times. It may be that using a LOOP instruction rather than a REP prefix / may help with this. / / In the absence of real diagnostic tools to analyse this problem, here we / provide a macro which expands to either form so we can build kernels for / experimental purposes. / Use "-D_USE_REP_PREFIX=1" to compile for the REP mode, / and nothing to compile for the LOOP mode. repeat .macro instr .if .defined _USE_REP_PREFIX rep instr .else repeat_\.macno: instr loop repeat_\.macno .endi .endm