Tweak how std/gif does interlace row replication
diff --git a/release/c/wuffs-unsupported-snapshot.c b/release/c/wuffs-unsupported-snapshot.c
index bdd505e..9dcb62a 100644
--- a/release/c/wuffs-unsupported-snapshot.c
+++ b/release/c/wuffs-unsupported-snapshot.c
@@ -8625,7 +8625,7 @@
static const uint8_t //
wuffs_gif__interlace_count[5] //
WUFFS_BASE__POTENTIALLY_UNUSED = {
- 0, 0, 1, 3, 7,
+ 0, 1, 2, 4, 8,
};
static const uint8_t //
@@ -11112,7 +11112,8 @@
wuffs_base__table_u8 v_tab = {0};
uint64_t v_i = 0;
uint64_t v_j = 0;
- uint32_t v_replicate_count = 0;
+ uint32_t v_replicate_y0 = 0;
+ uint32_t v_replicate_y1 = 0;
wuffs_base__slice_u8 v_replicate_dst = {0};
wuffs_base__slice_u8 v_replicate_src = {0};
@@ -11174,25 +11175,22 @@
if ((self->private_impl.f_num_decoded_frames_value == 0) &&
!self->private_impl.f_gc_has_transparent_index &&
(self->private_impl.f_interlace > 1)) {
- v_replicate_count = ((uint32_t)(
- wuffs_gif__interlace_count[self->private_impl.f_interlace]));
v_replicate_src =
wuffs_base__table_u8__row(v_tab, self->private_impl.f_dst_y);
- while (v_replicate_count > 0) {
- v_replicate_dst = wuffs_base__table_u8__row(
- v_tab, wuffs_base__u32__sat_add(self->private_impl.f_dst_y,
- v_replicate_count));
+ v_replicate_y0 =
+ wuffs_base__u32__sat_add(self->private_impl.f_dst_y, 1);
+ v_replicate_y1 = wuffs_base__u32__sat_add(
+ self->private_impl.f_dst_y,
+ ((uint32_t)(
+ wuffs_gif__interlace_count[self->private_impl.f_interlace])));
+ while (v_replicate_y0 < v_replicate_y1) {
+ v_replicate_dst = wuffs_base__table_u8__row(v_tab, v_replicate_y0);
wuffs_base__slice_u8__copy_from_slice(v_replicate_dst,
v_replicate_src);
- v_replicate_count -= 1;
+ v_replicate_y0 += 1;
}
self->private_impl.f_dirty_max_excl_y = wuffs_base__u32__max(
- self->private_impl.f_dirty_max_excl_y,
- wuffs_base__u32__sat_add(
- self->private_impl.f_dst_y,
- (((uint32_t)(wuffs_gif__interlace_count[self->private_impl
- .f_interlace])) +
- 1)));
+ self->private_impl.f_dirty_max_excl_y, v_replicate_y1);
}
wuffs_base__u32__sat_add_indirect(
&self->private_impl.f_dst_y,
diff --git a/std/gif/decode_gif.wuffs b/std/gif/decode_gif.wuffs
index 83e6d25..c06f21a 100644
--- a/std/gif/decode_gif.wuffs
+++ b/std/gif/decode_gif.wuffs
@@ -118,7 +118,7 @@
// to that maximum value (and therefore outside the frame rect).
pri const interlace_start array[5] base.u32 = [0xFFFFFFFF, 1, 2, 4, 0]
pri const interlace_delta array[5] base.u8 = [1, 2, 4, 8, 8]
-pri const interlace_count array[5] base.u8 = [0, 0, 1, 3, 7]
+pri const interlace_count array[5] base.u8 = [0, 1, 2, 4, 8]
pub struct decoder?(
width base.u32,
@@ -1104,7 +1104,8 @@
var tab table base.u8
var i base.u64
var j base.u64
- var replicate_count base.u32
+ var replicate_y0 base.u32
+ var replicate_y1 base.u32
var replicate_dst slice base.u8
var replicate_src slice base.u8
@@ -1178,16 +1179,16 @@
(not this.gc_has_transparent_index) and
(this.interlace > 1) {
- replicate_count = interlace_count[this.interlace] as base.u32
replicate_src = tab.row(y:this.dst_y)
- while replicate_count > 0 {
- replicate_dst = tab.row(y:this.dst_y ~sat+ replicate_count)
+ replicate_y0 = this.dst_y ~sat+ 1
+ replicate_y1 = this.dst_y ~sat+ (interlace_count[this.interlace] as base.u32)
+ while replicate_y0 < replicate_y1 {
+ assert replicate_y0 < 0xFFFFFFFF via "a < b: a < c; c <= b"(c:replicate_y1)
+ replicate_dst = tab.row(y:replicate_y0)
replicate_dst.copy_from_slice!(s:replicate_src)
- replicate_count -= 1
+ replicate_y0 += 1
}
-
- this.dirty_max_excl_y = this.dirty_max_excl_y.max(
- a:this.dst_y ~sat+ ((interlace_count[this.interlace] as base.u32) + 1))
+ this.dirty_max_excl_y = this.dirty_max_excl_y.max(a:replicate_y1)
}
this.dst_y ~sat+= interlace_delta[this.interlace] as base.u32
