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| author | Kevin O'Connor <kevin@koconnor.net> | 2017-05-16 11:59:10 -0400 |
|---|---|---|
| committer | Kevin O'Connor <kevin@koconnor.net> | 2017-06-12 14:59:38 -0400 |
| commit | dee3c1535d5550fab914cd181cbb02741d749e2a (patch) | |
| tree | d81323795bbb88b25c5e92c26cb31241e66ab9f8 | |
| parent | 8ebb33b1588d6be4241a70e7daabdab4eb076cd8 (diff) | |
| download | seabios-dee3c1535d5550fab914cd181cbb02741d749e2a.zip seabios-dee3c1535d5550fab914cd181cbb02741d749e2a.tar.gz seabios-dee3c1535d5550fab914cd181cbb02741d749e2a.tar.bz2 | |
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 <kevin@koconnor.net>
| -rw-r--r-- | src/stacks.c | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/src/stacks.c b/src/stacks.c index f4d15ce..2fe1bfb 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; } |