MQC/RAW decoder: use an artificial 0xFF 0xFF terminating marker.

This saves comparing the current pointer with the end of buffer pointer.
This results at least in tiny speed improvement for raw decoding, and
smaller code size for MQC as well.

This kills the remains of the raw.h/.c files that were only used for
decoding. Encoding using the mqc structure already.

1 files changed, 40 insertions, 5 deletions

diff --git a/src/lib/openjp2/mqc.c b/src/lib/openjp2/mqc.c
index bd4054c7..c4658cba 100644
--- a/src/lib/openjp2/mqc.c
+++ b/src/lib/openjp2/mqc.c
@@ -38,6 +38,8 @@
 
 #include "opj_includes.h"
 
+#include <assert.h>
+
 /** @defgroup MQC MQC - Implementation of an MQ-Coder */
 /*@{*/
 
@@ -423,17 +425,35 @@ void opj_mqc_segmark_enc(opj_mqc_t *mqc)
     }
 }
 
-OPJ_BOOL opj_mqc_init_dec(opj_mqc_t *mqc, OPJ_BYTE *bp, OPJ_UINT32 len)
+static void opj_mqc_init_dec_common(opj_mqc_t *mqc,
+                                    OPJ_BYTE *bp,
+                                    OPJ_UINT32 len,
+                                    OPJ_UINT32 extra_writable_bytes)
+{
+    (void)extra_writable_bytes;
+
+    assert(extra_writable_bytes >= OPJ_COMMON_CBLK_DATA_EXTRA);
+    mqc->start = bp;
+    mqc->end = bp + len;
+    /* Insert an artificial 0xFF 0xFF marker at end of the code block */
+    /* data so that the bytein routines stop on it. This saves us comparing */
+    /* the bp and end pointers */
+    /* But before inserting it, backup th bytes we will overwrite */
+    memcpy(mqc->backup, mqc->end, OPJ_COMMON_CBLK_DATA_EXTRA);
+    mqc->end[0] = 0xFF;
+    mqc->end[1] = 0xFF;
+    mqc->bp = bp;
+}
+void opj_mqc_init_dec(opj_mqc_t *mqc, OPJ_BYTE *bp, OPJ_UINT32 len,
+                      OPJ_UINT32 extra_writable_bytes)
 {
     /* Implements ISO 15444-1 C.3.5 Initialization of the decoder (INITDEC) */
     /* Note: alternate "J.1 - Initialization of the software-conventions */
     /* decoder" has been tried, but does */
     /* not bring any improvement. */
     /* See https://github.com/uclouvain/openjpeg/issues/921 */
+    opj_mqc_init_dec_common(mqc, bp, len, extra_writable_bytes);
     opj_mqc_setcurctx(mqc, 0);
-    mqc->start = bp;
-    mqc->end = bp + len;
-    mqc->bp = bp;
     if (len == 0) {
         mqc->c = 0xff << 16;
     } else {
@@ -444,7 +464,22 @@ OPJ_BOOL opj_mqc_init_dec(opj_mqc_t *mqc, OPJ_BYTE *bp, OPJ_UINT32 len)
     mqc->c <<= 7;
     mqc->ct -= 7;
     mqc->a = 0x8000;
-    return OPJ_TRUE;
+}
+
+
+void opj_mqc_raw_init_dec(opj_mqc_t *mqc, OPJ_BYTE *bp, OPJ_UINT32 len,
+                          OPJ_UINT32 extra_writable_bytes)
+{
+    opj_mqc_init_dec_common(mqc, bp, len, extra_writable_bytes);
+    mqc->c = 0;
+    mqc->ct = 0;
+}
+
+
+void opq_mqc_finish_dec(opj_mqc_t *mqc)
+{
+    /* Restore the bytes overwritten by opj_mqc_init_dec_common() */
+    memcpy(mqc->end, mqc->backup, OPJ_COMMON_CBLK_DATA_EXTRA);
 }
 
 void opj_mqc_resetstates(opj_mqc_t *mqc)