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Optimise bios_putchar for speed(!) by avoiding two separate real-mode

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calls.  This does make a visible difference when clearing the screen with
werase() inside bochs or qemu.
This commit is contained in:
Michael Brown 2006-12-19 01:15:05 +00:00
parent e85bf52446
commit 0aa1223264
1 changed files with 16 additions and 11 deletions
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27
src/arch/i386/firmware/pcbios/bios_console.c
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@ -148,26 +148,31 @@ static struct ansiesc_context bios_ansiesc_ctx = {
* @v character Character to be printed
*/
static void bios_putchar ( int character ) {
int discard_a, discard_b, discard_c;
/* Intercept ANSI escape sequences */
character = ansiesc_process ( &bios_ansiesc_ctx, character );
if ( character < 0 )
return;
/* Set attribute for printable characters */
if ( character >= 0x20 ) {
__asm__ __volatile__ ( REAL_CODE ( "sti\n\t"
"int $0x10\n\t"
"cli\n\t" )
: : "a" ( 0x0920 ), "b" ( bios_attr ),
"c" ( 1 ) );
}
/* Print the character */
/* Print character with attribute */
__asm__ __volatile__ ( REAL_CODE ( "sti\n\t"
/* Skip non-printable characters */
"cmpb $0x20, %%al\n\t"
"jb 1f\n\t"
/* Set attribute */
"movw $0x0001, %%cx\n\t"
"movb $0x09, %%ah\n\t"
"int $0x10\n\t"
"\n1:\n\t"
/* Print character */
"xorw %%bx, %%bx\n\t"
"movb $0x0e, %%ah\n\t"
"int $0x10\n\t"
"cli\n\t" )
: : "a" ( character | 0x0e00 ), "b" ( 0 )
: "=a" ( discard_a ), "=b" ( discard_b ),
"=c" ( discard_c )
: "a" ( character ), "b" ( bios_attr )
: "ebp" );
}