From 2ba861c37cb5032d1fa90a7c9298f6e08a0f5413 Mon Sep 17 00:00:00 2001
From: Even Rouault <even.rouault@spatialys.com>
Date: Thu, 1 Jun 2017 19:42:03 +0200
Subject: [PATCH] Optimize opj_t1_update_flags()

---
 src/lib/openjp2/t1.c | 48 +++++++++-----------------------------------
 src/lib/openjp2/t1.h |  1 +
 2 files changed, 11 insertions(+), 38 deletions(-)

diff --git a/src/lib/openjp2/t1.c b/src/lib/openjp2/t1.c
index d5fba6f9..eb69939c 100644
--- a/src/lib/openjp2/t1.c
+++ b/src/lib/openjp2/t1.c
@@ -306,58 +306,30 @@ static OPJ_INT16 opj_t1_getnmsedec_ref(OPJ_UINT32 x, OPJ_UINT32 bitpos)
 static INLINE void opj_t1_update_flags(opj_flag_t *flagsp, OPJ_UINT32 ci,
                                        OPJ_UINT32 s, OPJ_UINT32 stride)
 {
-    /* set up to point to the north and south data points' flags words, if required */
-    opj_flag_t* north;
-    opj_flag_t* south;
+    /* east */
+    flagsp[-1] |= T1_SIGMA_5 << (3U * ci);
 
     /* mark target as significant */
-    *flagsp |= T1_SIGMA_4 << (3U * ci);
+    *flagsp |= ((s << T1_CHI_1_I) | T1_SIGMA_4) << (3U * ci);
+
+    /* west */
+    flagsp[1] |= T1_SIGMA_3 << (3U * ci);
 
     /* north-west, north, north-east */
     if (ci == 0U) {
-        north = flagsp - stride;
-        *north |= T1_SIGMA_16;
+        opj_flag_t* north = flagsp - stride;
+        *north |= (s << T1_CHI_5_I) | T1_SIGMA_16;
         north[-1] |= T1_SIGMA_17;
         north[1] |= T1_SIGMA_15;
     }
 
     /* south-west, south, south-east */
     if (ci == 3U) {
-        south = flagsp + stride;
-        *south |= T1_SIGMA_1;
+        opj_flag_t* south = flagsp + stride;
+        *south |= (s << T1_CHI_0_I) | T1_SIGMA_1;
         south[-1] |= T1_SIGMA_2;
         south[1] |= T1_SIGMA_0;
     }
-
-    /* east */
-    flagsp[-1] |= T1_SIGMA_5 << (3U * ci);
-
-    /* west */
-    flagsp[1] |= T1_SIGMA_3 << (3U * ci);
-
-    if (s) {
-        switch (ci) {
-        case 0U: {
-            *flagsp |= T1_CHI_1;
-            north = flagsp - stride;
-            *north |= T1_CHI_5;
-            break;
-        }
-        case 1:
-            *flagsp |= T1_CHI_2;
-            break;
-        case 2:
-            *flagsp |= T1_CHI_3;
-            break;
-        case 3: {
-            *flagsp |= T1_CHI_4;
-            south = flagsp + stride;
-            *south |= T1_CHI_0;
-            break;
-        }
-
-        }
-    }
 }
 
 /**
diff --git a/src/lib/openjp2/t1.h b/src/lib/openjp2/t1.h
index a6982ce2..17123265 100644
--- a/src/lib/openjp2/t1.h
+++ b/src/lib/openjp2/t1.h
@@ -124,6 +124,7 @@ in T1.C are used by some function in TCD.C.
 #define T1_MU_3     (1U << 29)
 #define T1_PI_3     (1U << 30)
 #define T1_CHI_5    (1U << 31)
+#define T1_CHI_5_I  31
 
 /** As an example, the bits T1_SIGMA_3, T1_SIGMA_4 and T1_SIGMA_5
  *  indicate the significance state of the west neighbour of data point zero