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lavc/dxvenc: fix big-endian issues in dxv_compress_dxt1

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We were using a mix of pointers to local variables read via AV_RL32/64 and
pointers directly to the texture buffer as keys to interact with the lookback
hashtables. On big-endian systems, these produced different values. This change
makes all hashtable interactions use direct pointers to the texture buffer and
only invokves AV_RL32 in the event of a lookback hashtable miss.

Signed-off-by: Emma Worley <emma@emma.gg>
This commit is contained in:
Emma Worley
2025-06-03 22:38:21 -07:00
parent 3be9b3f156
commit a4c1a5b084
1 changed files with 9 additions and 13 deletions
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22
libavcodec/dxvenc.c
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@ -100,8 +100,7 @@ static int dxv_compress_dxt1(AVCodecContext *avctx)
DXVEncContext *ctx = avctx->priv_data;
PutByteContext *pbc = &ctx->pbc;
void *value;
uint64_t combo;
uint32_t color, lut, idx, combo_idx, prev_pos, old_pos, state = 16, pos = 0, op = 0;
uint32_t idx, combo_idx, prev_pos, old_pos, state = 16, pos = 0, op = 0;
ff_hashtable_clear(ctx->color_ht);
ff_hashtable_clear(ctx->lut_ht);
@ -117,8 +116,7 @@ static int dxv_compress_dxt1(AVCodecContext *avctx)
pos++;
while (pos + 2 <= ctx->tex_size / 4) {
combo = AV_RL64(ctx->tex_data + pos * 4);
combo_idx = ff_hashtable_get(ctx->combo_ht, &combo, &prev_pos) ? pos - prev_pos : 0;
combo_idx = ff_hashtable_get(ctx->combo_ht, ctx->tex_data + pos * 4, &prev_pos) ? pos - prev_pos : 0;
idx = combo_idx;
PUSH_OP(2);
if (pos >= LOOKBACK_WORDS) {
@ -126,36 +124,34 @@ static int dxv_compress_dxt1(AVCodecContext *avctx)
if (ff_hashtable_get(ctx->combo_ht, ctx->tex_data + old_pos * 4, &prev_pos) && prev_pos <= old_pos)
ff_hashtable_delete(ctx->combo_ht, ctx->tex_data + old_pos * 4);
}
ff_hashtable_set(ctx->combo_ht, &combo, &pos);
ff_hashtable_set(ctx->combo_ht, ctx->tex_data + pos * 4, &pos);
color = AV_RL32(ctx->tex_data + pos * 4);
if (!combo_idx) {
idx = ff_hashtable_get(ctx->color_ht, &color, &prev_pos) ? pos - prev_pos : 0;
idx = ff_hashtable_get(ctx->color_ht, ctx->tex_data + pos * 4, &prev_pos) ? pos - prev_pos : 0;
PUSH_OP(2);
if (!idx)
bytestream2_put_le32(pbc, color);
bytestream2_put_le32(pbc, AV_RL32(ctx->tex_data + pos * 4));
}
if (pos >= LOOKBACK_WORDS) {
old_pos = pos - LOOKBACK_WORDS;
if (ff_hashtable_get(ctx->color_ht, ctx->tex_data + old_pos * 4, &prev_pos) && prev_pos <= old_pos)
ff_hashtable_delete(ctx->color_ht, ctx->tex_data + old_pos * 4);
}
ff_hashtable_set(ctx->color_ht, &color, &pos);
ff_hashtable_set(ctx->color_ht, ctx->tex_data + pos * 4, &pos);
pos++;
lut = AV_RL32(ctx->tex_data + pos * 4);
if (!combo_idx) {
idx = ff_hashtable_get(ctx->lut_ht, &lut, &prev_pos) ? pos - prev_pos : 0;
idx = ff_hashtable_get(ctx->lut_ht, ctx->tex_data + pos * 4, &prev_pos) ? pos - prev_pos : 0;
PUSH_OP(2);
if (!idx)
bytestream2_put_le32(pbc, lut);
bytestream2_put_le32(pbc, AV_RL32(ctx->tex_data + pos * 4));
}
if (pos >= LOOKBACK_WORDS) {
old_pos = pos - LOOKBACK_WORDS;
if (ff_hashtable_get(ctx->lut_ht, ctx->tex_data + old_pos * 4, &prev_pos) && prev_pos <= old_pos)
ff_hashtable_delete(ctx->lut_ht, ctx->tex_data + old_pos * 4);
}
ff_hashtable_set(ctx->lut_ht, &lut, &pos);
ff_hashtable_set(ctx->lut_ht, ctx->tex_data + pos * 4, &pos);
pos++;
}