1 files changed, 71 insertions, 0 deletions
diff --git a/yuvbench/yuvbench_bad.c b/yuvbench/yuvbench_bad.c
index e69de29..da263d4 100644
--- a/yuvbench/yuvbench_bad.c
+++ b/yuvbench/yuvbench_bad.c
@@ -0,0 +1,71 @@
+#include "yuvbench.h"
+
+static inline uint8_t clamp8(int32_t x)
+{
+    if (x < 0) {
+        return 0;
+    }
+    if (x > 255) {
+        return 255;
+    }
+    return x;
+}
+
+static bool yuvbench_bad_init(Ctx* ctx)
+{
+    return (ctx->inp_w % 2 == 0) && (ctx->inp_h % 2 == 0);
+}
+
+static bool yuvbench_bad_convert(Ctx* ctx)
+{
+    const uint32_t w = ctx->inp_w;
+    const uint32_t h = ctx->inp_h;
+    
+    // Input planes
+    const uint8_t* Y  = (const uint8_t*)ctx->inp_buf;
+    const uint8_t* Cb = Y + (w * h);
+    const uint8_t* Cr = Cb + (w / 2 * h / 2);
+
+    // Output plane
+    uint8_t* RGB = (uint8_t*)ctx->out_buf;
+
+    // Iterate over 2x2 input blocks
+    for (uint32_t y = 0; y < h; y += 2) {
+    for (uint32_t x = 0; x < w; x += 2) {
+        uint8_t cb = Cb[(y / 2) * (w / 2) + (x / 2)]; // 0.5x sample
+        uint8_t cr = Cr[(y / 2) * (w / 2) + (x / 2)]; // 0.5x sample
+        for (uint32_t dy = 0; dy < 2; ++dy) {
+        for (uint32_t dx = 0; dx < 2; ++dx) {
+            uint32_t py = y + dy;
+            uint32_t px = x + dx;
+
+            const uint8_t yval = Y[py * w + px]; // 1.0x sample
+
+            // ref: https://en.wikipedia.org/wiki/Y%E2%80%B2UV#HDTV_with_BT.709
+            int32_t y2 = (int32_t)yval - 16;
+            int32_t cb2 = (int32_t)cb - 128;
+            int32_t cr2 = (int32_t)cr - 128;
+            int32_t r = 1164 * y2 +  1856 * cr2;
+            int32_t g = 1164 * y2 -  187  * cb2 - 468 * cr2;
+            int32_t b = 1164 * y2 +  2148 * cb2;
+            r = (r + 500) / 1000;
+            g = (g + 500) / 1000;
+            b = (b + 500) / 1000;
+            size_t idx = (py * w + px) * 3;
+            RGB[idx + 0] = clamp8(r);
+            RGB[idx + 1] = clamp8(g);
+            RGB[idx + 2] = clamp8(b);
+        }
+        }
+    }
+    }
+    return true;
+}
+
+Backend yuvbench_bad(void)
+{
+  Backend b = { 0 };
+  b.init_fn = yuvbench_bad_init;
+  b.convert_fn = yuvbench_bad_convert;
+  return b;
+}