Accelerated 4:2:2 upsampling routine for ARM (improves performance ~20-30% when decompressing 4:2:2 JPEGs using fancy upsampling)

simd/jsimd_arm.c

@@ -338,6 +338,15 @@ jsimd_can_h2v1_fancy_upsample (void)
 {
   init_simd();
 
+  /* The code is optimised for these values only */
+  if (BITS_IN_JSAMPLE != 8)
+    return 0;
+  if (sizeof(JDIMENSION) != 4)
+    return 0;
+
+  if (simd_support & JSIMD_ARM_NEON)
+    return 1;
+
   return 0;
 }
 
@@ -355,6 +364,9 @@ jsimd_h2v1_fancy_upsample (j_decompress_ptr cinfo,
                            JSAMPARRAY input_data,
                            JSAMPARRAY * output_data_ptr)
 {
+  if (simd_support & JSIMD_ARM_NEON)
+    jsimd_h2v1_fancy_upsample_neon(cinfo->max_v_samp_factor,
+        compptr->downsampled_width, input_data, output_data_ptr);
 }
 
 GLOBAL(int)