From 84ae5cdefce657cd713393277b0635d19e005a9c Mon Sep 17 00:00:00 2001
From: Wan-Teh Chang <wtc@google.com>
Date: Thu, 15 Aug 2024 15:26:09 -0700
Subject: [PATCH] Minor comment fixes for the mini box code

Change
   bit(2) version;
to
   bit(2) version = 0;
to match the spec exactly.
---
 include/avif/internal.h | 2 +-
 src/read.c              | 4 +++-
 src/write.c             | 4 ++--
 3 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/include/avif/internal.h b/include/avif/internal.h
index c285900a0f..36c373790f 100644
--- a/include/avif/internal.h
+++ b/include/avif/internal.h
@@ -692,7 +692,7 @@ AVIF_NODISCARD avifBool avifROStreamReadBoxHeader(avifROStream * stream, avifBox
 AVIF_NODISCARD avifBool avifROStreamReadBoxHeaderPartial(avifROStream * stream, avifBoxHeader * header, avifBool topLevel); // This doesn't require that the full box can fit in the stream
 AVIF_NODISCARD avifBool avifROStreamReadVersionAndFlags(avifROStream * stream, uint8_t * version, uint32_t * flags); // version and flags ptrs are both optional
 AVIF_NODISCARD avifBool avifROStreamReadAndEnforceVersion(avifROStream * stream, uint8_t enforcedVersion); // currently discards flags
-// The following functions can write non-aligned bits.
+// The following functions can read non-aligned bits.
 AVIF_NODISCARD avifBool avifROStreamReadBits8(avifROStream * stream, uint8_t * v, size_t bitCount);
 AVIF_NODISCARD avifBool avifROStreamReadBits(avifROStream * stream, uint32_t * v, size_t bitCount);
 
diff --git a/src/read.c b/src/read.c
index ded677f773..c8bc2c9bcc 100644
--- a/src/read.c
+++ b/src/read.c
@@ -3572,7 +3572,7 @@ static avifResult avifParseMinimizedImageBox(avifMeta * meta, uint64_t rawOffset
     meta->fromMiniBox = AVIF_TRUE;
 
     uint32_t version;
-    AVIF_CHECKERR(avifROStreamReadBits(&s, &version, 2), AVIF_RESULT_BMFF_PARSE_FAILED); // bit(2) version;
+    AVIF_CHECKERR(avifROStreamReadBits(&s, &version, 2), AVIF_RESULT_BMFF_PARSE_FAILED); // bit(2) version = 0;
     AVIF_CHECKERR(version == 0, AVIF_RESULT_BMFF_PARSE_FAILED);
 
     // flags
@@ -3818,6 +3818,7 @@ static avifResult avifParseMinimizedImageBox(avifMeta * meta, uint64_t rawOffset
     // Chunks
     avifCodecConfigurationBox alphaItemCodecConfig = { 0 };
     if (hasAlpha && alphaItemDataSize != 0 && alphaItemCodecConfigSize != 0) {
+        // 'av1C' always uses 4 bytes.
         AVIF_CHECKERR(alphaItemCodecConfigSize == 4, AVIF_RESULT_BMFF_PARSE_FAILED);
         AVIF_CHECKERR(avifParseCodecConfiguration(&s, &alphaItemCodecConfig, (const char *)codecConfigType, diag),
                       AVIF_RESULT_BMFF_PARSE_FAILED); // unsigned int(8) alpha_item_codec_config[alpha_item_codec_config_size];
@@ -3825,6 +3826,7 @@ static avifResult avifParseMinimizedImageBox(avifMeta * meta, uint64_t rawOffset
     // if (hdr_flag && gainmap_flag && gainmap_item_codec_config_size > 0)
     //     unsigned int(8) gainmap_item_codec_config[gainmap_item_codec_config_size];
     avifCodecConfigurationBox mainItemCodecConfig = { 0 };
+    // 'av1C' always uses 4 bytes.
     AVIF_CHECKERR(mainItemCodecConfigSize == 4, AVIF_RESULT_BMFF_PARSE_FAILED);
     AVIF_CHECKERR(avifParseCodecConfiguration(&s, &mainItemCodecConfig, (const char *)codecConfigType, diag),
                   AVIF_RESULT_BMFF_PARSE_FAILED); // unsigned int(8) main_item_codec_config[main_item_codec_config_size];
diff --git a/src/write.c b/src/write.c
index 027e588b1e..10b250acf3 100644
--- a/src/write.c
+++ b/src/write.c
@@ -2463,13 +2463,13 @@ static avifResult avifEncoderWriteMiniBox(avifEncoder * encoder, avifRWStream *
 
     const uint32_t smallDimensionsFlag = image->width <= (1 << 7) && image->height <= (1 << 7);
     const uint32_t codecConfigSize = 4;                                  // 'av1C' always uses 4 bytes.
-    const uint32_t fewCodecConfigBytesFlag = codecConfigSize < (1 << 3); // 'av1C' always uses 4 bytes.
+    const uint32_t fewCodecConfigBytesFlag = codecConfigSize < (1 << 3);
     const uint32_t fewItemDataBytesFlag = colorData->size <= (1 << 15) && (!alphaData || alphaData->size < (1 << 15));
     const uint32_t fewMetadataBytesFlag = image->icc.size <= (1 << 10) && image->exif.size <= (1 << 10) && image->xmp.size <= (1 << 10);
 
     avifBoxMarker mini;
     AVIF_CHECKRES(avifRWStreamWriteBox(s, "mini", AVIF_BOX_SIZE_TBD, &mini));
-    AVIF_CHECKRES(avifRWStreamWriteBits(s, 0, 2)); // bit(2) version;
+    AVIF_CHECKRES(avifRWStreamWriteBits(s, 0, 2)); // bit(2) version = 0;
 
     // flags
     AVIF_CHECKRES(avifRWStreamWriteBits(s, hasExplicitCodecTypes, 1));    // bit(1) explicit_codec_types_flag;