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Build boot2 with -mregparm=3, ie. pass upto 3 arguments via registers.

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This modifies CFLAGS and tweaks sio.S to use the new calling convention.
The sio_init() and sio_putc() prototypes are modified so that other
users of this code know the correct calling convention.

This makes the code smaller when compiled with clang.

Reviewed by:    jhb
Tested by:      me and Freddie Cash <fjwcash gmail com>
This commit is contained in:
Roman Divacky 2011-04-04 18:23:55 +00:00
parent aa977fc70e
commit 57ac2e1286
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=220337
3 changed files with 12 additions and 10 deletions
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1
sys/boot/i386/boot2/Makefile
View File

@ -31,6 +31,7 @@ CFLAGS= -Os \
-fno-unit-at-a-time \
-mno-align-long-strings \
-mrtd \
-mregparm=3 \
-D${BOOT2_UFS} \
-DFLAGS=${BOOT_BOOT1_FLAGS} \
-DSIOPRT=${BOOT_COMCONSOLE_PORT} \

4
sys/boot/i386/boot2/lib.h
View File

@ -17,8 +17,8 @@
* $FreeBSD$
*/
void sio_init(int);
void sio_init(int) __attribute__((regparm (3)));
void sio_flush(void);
void sio_putc(int);
void sio_putc(int) __attribute__((regparm (3)));
int sio_getc(void);
int sio_ischar(void);

17
sys/boot/i386/boot2/sio.S
View File

@ -26,14 +26,14 @@
/* void sio_init(int div) */
sio_init: movw $SIO_PRT+0x3,%dx # Data format reg
sio_init: pushl %eax
movw $SIO_PRT+0x3,%dx # Data format reg
movb $SIO_FMT|0x80,%al # Set format
outb %al,(%dx) # and DLAB
pushl %edx # Save
subb $0x3,%dl # Divisor latch reg
movl 0x8(%esp),%eax # Set
popl %eax
outw %ax,(%dx) # BPS
popl %edx # Restore
movw $SIO_PRT+0x3,%dx # Data format reg
movb $SIO_FMT,%al # Clear
outb %al,(%dx) # DLAB
incl %edx # Modem control reg
@ -41,7 +41,7 @@ sio_init: movw $SIO_PRT+0x3,%dx # Data format reg
outb %al,(%dx) # DTR
incl %edx # Line status reg
call sio_flush
ret $0x4
ret
/* void sio_flush(void) */
@ -52,17 +52,18 @@ sio_flush: call sio_ischar # Check for character
/* void sio_putc(int c) */
sio_putc: movw $SIO_PRT+0x5,%dx # Line status reg
sio_putc: pushl %eax
movw $SIO_PRT+0x5,%dx # Line status reg
xor %ecx,%ecx # Timeout
movb $0x40,%ch # counter
sio_putc.1: inb (%dx),%al # Transmitter
testb $0x20,%al # buffer empty?
loopz sio_putc.1 # No
jz sio_putc.2 # If timeout
movb 0x4(%esp,1),%al # Get character
popl %eax # Get the character
subb $0x5,%dl # Transmitter hold reg
outb %al,(%dx) # Write character
sio_putc.2: ret $0x4 # To caller
sio_putc.2: ret # To caller
/* int sio_getc(void) */