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| author |   Jiri Slaby <jslaby@suse.cz> | 2020-08-18 10:56:59 +0200 |
|---|---|---|
| committer |   Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-08-18 13:45:21 +0200 |
| commit | d7c91c50815beebe14905292404b048a26147c07 (patch) | |
| tree | 0eb4daa976ecf4718f8db5297150e5647650ae4d /drivers/tty/vt/vc_screen.c | |
| parent | vc_screen: extract vcs_write_buf (diff) | |
| download | linux-dev-d7c91c50815beebe14905292404b048a26147c07.tar.xz linux-dev-d7c91c50815beebe14905292404b048a26147c07.zip | |
vc_screen: eliminate ifdefs from vcs_write_buf
Introduce a new inline function called vc_compile_le16 and do the shifts
and ORs there. Depending on LE x BE.
I tried cpu_to_le16, but it ends up with worse assembly on BE for
whatever reason -- the compiler seems to be unable to optimize the swap.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20200818085706.12163-9-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/vt/vc_screen.c')
| -rw-r--r-- | drivers/tty/vt/vc_screen.c | 29 |
1 files changed, 17 insertions, 12 deletions
diff --git a/drivers/tty/vt/vc_screen.c b/drivers/tty/vt/vc_screen.c index 10a26fd5f1b7..36b967825f68 100644 --- a/drivers/tty/vt/vc_screen.c +++ b/drivers/tty/vt/vc_screen.c @@ -481,6 +481,19 @@ static u16 *vcs_write_buf_noattr(struct vc_data *vc, const char *con_buf, return org; } +/* + * Compilers (gcc 10) are unable to optimize the swap in cpu_to_le16. So do it + * the poor man way. + */ +static inline u16 vc_compile_le16(u8 hi, u8 lo) +{ +#ifdef __BIG_ENDIAN + return (lo << 8u) | hi; +#else + return (hi << 8u) | lo; +#endif +} + static u16 *vcs_write_buf(struct vc_data *vc, const char *con_buf, unsigned int pos, unsigned int count, bool viewed, u16 **org0) { @@ -513,13 +526,8 @@ static u16 *vcs_write_buf(struct vc_data *vc, const char *con_buf, if (pos & 1) { count--; c = *con_buf++; -#ifdef __BIG_ENDIAN - vcs_scr_writew(vc, c | - (vcs_scr_readw(vc, org) & 0xff00), org); -#else - vcs_scr_writew(vc, (c << 8) | - (vcs_scr_readw(vc, org) & 0xff), org); -#endif + vcs_scr_writew(vc, vc_compile_le16(c, vcs_scr_readw(vc, org)), + org); org++; pos++; if (++col == maxcol) { @@ -551,11 +559,8 @@ static u16 *vcs_write_buf(struct vc_data *vc, const char *con_buf, /* odd pos -- the remaining character */ c = *con_buf++; -#ifdef __BIG_ENDIAN - vcs_scr_writew(vc, (vcs_scr_readw(vc, org) & 0xff) | (c << 8), org); -#else - vcs_scr_writew(vc, (vcs_scr_readw(vc, org) & 0xff00) | c, org); -#endif + vcs_scr_writew(vc, vc_compile_le16(vcs_scr_readw(vc, org) >> 8, c), + org); return org; } |