From dee3c1535d5550fab914cd181cbb02741d749e2a Mon Sep 17 00:00:00 2001 From: Kevin O'Connor Date: Tue, 16 May 2017 11:59:10 -0400 Subject: stacks: There is no need to disable NMI if it is already disabled Don't write to the cmos index port on a mode switch if NMI is already disabled. This reduces the number of outb() calls. Signed-off-by: Kevin O'Connor --- src/stacks.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) (limited to 'src/stacks.c') diff --git a/src/stacks.c b/src/stacks.c index f4d15ce9..2fe1bfbd 100644 --- a/src/stacks.c +++ b/src/stacks.c @@ -66,8 +66,10 @@ call32_prep(u8 method) // Backup cmos index register and disable nmi u8 cmosindex = inb(PORT_CMOS_INDEX); - outb(cmosindex | NMI_DISABLE_BIT, PORT_CMOS_INDEX); - inb(PORT_CMOS_DATA); + if (!(cmosindex & NMI_DISABLE_BIT)) { + outb(cmosindex | NMI_DISABLE_BIT, PORT_CMOS_INDEX); + inb(PORT_CMOS_DATA); + } SET_LOW(Call16Data.cmosindex, cmosindex); SET_LOW(Call16Data.method, method); @@ -103,8 +105,11 @@ call32_post(void) } // Restore cmos index register - outb(GET_LOW(Call16Data.cmosindex), PORT_CMOS_INDEX); - inb(PORT_CMOS_DATA); + u8 cmosindex = GET_LOW(Call16Data.cmosindex); + if (!(cmosindex & NMI_DISABLE_BIT)) { + outb(cmosindex, PORT_CMOS_INDEX); + inb(PORT_CMOS_DATA); + } return method; } -- cgit