Function avifImageApplyExpression32b

src/sampletransform.c:284–351

AVIF_ARRAY_DECLARE(avifSampleTransformStack32b, int32_t, elements);

static avifResult avifImageApplyExpression32b(avifImage * dstImage,
                                              const avifSampleTransformExpression * expression,
                                              const avifImage * inputImageItems[],
                                              avifPlanesFlags planes,
                                              int32_t * stack,
                                              uint32_t stackCapacity)
{
    // This slow path could be avoided by recognizing the recipe thanks to avifSampleTransformExpressionToRecipe()
    // and having a dedicated optimized implementation for each recipe.

    const int32_t minValue = 0;
    const int32_t maxValue = (1 << dstImage->depth) - 1;

    const avifBool skipColor = !(planes & AVIF_PLANES_YUV);
    const avifBool skipAlpha = !(planes & AVIF_PLANES_A);
    for (int c = AVIF_CHAN_Y; c <= AVIF_CHAN_A; ++c) {
        const avifBool alpha = c == AVIF_CHAN_A;
        if ((skipColor && !alpha) || (skipAlpha && alpha)) {
            continue;
        }

        const uint32_t planeWidth = avifImagePlaneWidth(dstImage, c);
        const uint32_t planeHeight = avifImagePlaneHeight(dstImage, c);
        for (uint32_t y = 0; y < planeHeight; ++y) {
            for (uint32_t x = 0; x < planeWidth; ++x) {
                uint32_t stackSize = 0;
                for (uint32_t t = 0; t < expression->count; ++t) {
                    const avifSampleTransformToken * token = &expression->tokens[t];
                    if (token->type == AVIF_SAMPLE_TRANSFORM_CONSTANT) {
                        AVIF_ASSERT_OR_RETURN(stackSize < stackCapacity);
                        stack[stackSize++] = token->constant;
                    } else if (token->type == AVIF_SAMPLE_TRANSFORM_INPUT_IMAGE_ITEM_INDEX) {
                        const avifImage * image = inputImageItems[token->inputImageItemIndex - 1]; // 1-based
                        const uint8_t * row = avifImagePlane(image, c);
                        AVIF_ASSERT_OR_RETURN(row != NULL);
                        row += (size_t)avifImagePlaneRowBytes(image, c) * y;
                        AVIF_ASSERT_OR_RETURN(stackSize < stackCapacity);
                        stack[stackSize++] = avifImageUsesU16(image) ? ((const uint16_t *)row)[x] : row[x];
                    } else if (token->type == AVIF_SAMPLE_TRANSFORM_NEGATION || token->type == AVIF_SAMPLE_TRANSFORM_ABSOLUTE ||
                               token->type == AVIF_SAMPLE_TRANSFORM_NOT || token->type == AVIF_SAMPLE_TRANSFORM_BSR) {
                        AVIF_ASSERT_OR_RETURN(stackSize >= 1);
                        stack[stackSize - 1] = avifSampleTransformOperation32bOneOperand(stack[stackSize - 1], token->type);
                        // Pop one and push one.
                    } else {
                        AVIF_ASSERT_OR_RETURN(stackSize >= 2);
                        stack[stackSize - 2] =
                            avifSampleTransformOperation32bTwoOperands(stack[stackSize - 2], stack[stackSize - 1], token->type);
                        stackSize--; // Pop two and push one.
                    }
                }
                AVIF_ASSERT_OR_RETURN(stackSize == 1);
                // Fit to the range defined by the PixelInformationProperty.
                // The limited/full range is ignored, like in other libavif encoding and decoding paths.
                stack[0] = AVIF_CLAMP(stack[0], minValue, maxValue);

                uint8_t * row = avifImagePlane(dstImage, c);
                AVIF_ASSERT_OR_RETURN(row != NULL);
                row += (size_t)avifImagePlaneRowBytes(dstImage, c) * y;