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 <[email protected]> --- drivers/tty/vt/vc_screen.c | 29 +++++++++++++++++------------ 1 file 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; } -- 2.28.0
