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sm501: Fix and optimize overlap check 

When doing reverse blit we need to check if source and dest overlap
but it is not trivial due to possible different base and pitch of
source and dest. Do rectangle overlap if base and pitch match,
otherwise just check if memory area containing the rects overlaps so
rects could possibly overlap.

Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
Message-Id: <20200624164737.A941374633D@zero.eik.bme.hu>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
This commit is contained in:
BALATON Zoltan 2020-06-24 18:42:18 +02:00 committed by Gerd Hoffmann
parent d8327a6869
commit 9982c605a7
1 changed files with 16 additions and 10 deletions
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26
hw/display/sm501.c
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@ -690,6 +690,7 @@ static void sm501_2d_operation(SM501State *s)
unsigned int dst_pitch = (s->twoD_pitch >> 16) & 0x1FFF;
int crt = (s->dc_crt_control & SM501_DC_CRT_CONTROL_SEL) ? 1 : 0;
int fb_len = get_width(s, crt) * get_height(s, crt) * get_bpp(s, crt);
bool overlap = false;
if ((s->twoD_stretch >> 16) & 0xF) {
qemu_log_mask(LOG_UNIMP, "sm501: only XY addressing is supported.\n");
@ -784,16 +785,21 @@ static void sm501_2d_operation(SM501State *s)
ldn_he_p(&s->local_mem[src_base + si], bypp));
break;
}
/* Check for overlaps, this could be made more exact */
uint32_t sb, se, db, de;
sb = src_base + src_x + src_y * (width + src_pitch);
se = sb + width + height * (width + src_pitch);
db = dst_base + dst_x + dst_y * (width + dst_pitch);
de = db + width + height * (width + dst_pitch);
if (rtl && ((db >= sb && db <= se) || (de >= sb && de <= se))) {
/* regions may overlap: copy via temporary */
int llb = width * bypp;
int tmp_stride = DIV_ROUND_UP(llb, sizeof(uint32_t));
/* If reverse blit do simple check for overlaps */
if (rtl && src_base == dst_base && src_pitch == dst_pitch) {
overlap = (src_x < dst_x + width && src_x + width > dst_x &&
src_y < dst_y + height && src_y + height > dst_y);
} else if (rtl) {
unsigned int sb, se, db, de;
sb = src_base + (src_x + src_y * src_pitch) * bypp;
se = sb + (width + (height - 1) * src_pitch) * bypp;
db = dst_base + (dst_x + dst_y * dst_pitch) * bypp;
de = db + (width + (height - 1) * dst_pitch) * bypp;
overlap = (db < se && sb < de);
}
if (overlap) {
/* pixman can't do reverse blit: copy via temporary */
int tmp_stride = DIV_ROUND_UP(width * bypp, sizeof(uint32_t));
uint32_t *tmp = tmp_buf;
if (tmp_stride * sizeof(uint32_t) * height > sizeof(tmp_buf)) {