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Update some comments

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This commit is contained in:
Gregory Nutt
2015-04-13 07:39:56 -06:00
parent bf59ead547
commit 3d6161a7aa
2 changed files with 20 additions and 13 deletions
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fs/fat/fs_fat32util.c
+20 -6
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@@ -296,7 +296,10 @@ static int fat_checkbootrecord(struct fat_mountpt_s *fs)
uint16_t fat_getuint16(uint8_t *ptr)
{
/* Byte-by-byte transfer is still necessary if the address is un-aligned */
/* NOTE that (1) this operation is independent of endian-ness and that (2)
* byte-by-byte transfer is necessary in any case because the address may be
* unaligned.
*/
return ((uint16_t)ptr[1] << 8) | ptr[0];
}
@@ -307,7 +310,10 @@ uint16_t fat_getuint16(uint8_t *ptr)
uint32_t fat_getuint32(uint8_t *ptr)
{
/* Byte-by-byte transfer is still necessary if the address is un-aligned */
/* NOTE that (1) this operation is independent of endian-ness and that (2)
* byte-by-byte transfer is necessary in any case because the address may be
* unaligned.
*/
return ((uint32_t)fat_getuint16(&ptr[2]) << 16) | fat_getuint16(&ptr[0]);
}
@@ -321,13 +327,17 @@ void fat_putuint16(uint8_t *ptr, uint16_t value16)
uint8_t *val = (uint8_t*)&value16;
#ifdef CONFIG_ENDIAN_BIG
/* The bytes always have to be swapped if the target is big-endian */
/* If the target is big-endian then the bytes always have to be swapped so
* that the representation is litle endian in the file system.
*/
ptr[0] = val[1];
ptr[1] = val[0];
#else
/* Byte-by-byte transfer is still necessary if the address is un-aligned */
/* Byte-by-byte transfer is still necessary because the address may be
* un-aligned.
*/
ptr[0] = val[0];
ptr[1] = val[1];
@@ -343,13 +353,17 @@ void fat_putuint32(uint8_t *ptr, uint32_t value32)
uint16_t *val = (uint16_t*)&value32;
#ifdef CONFIG_ENDIAN_BIG
/* The bytes always have to be swapped if the target is big-endian */
/* If the target is big-endian then the bytes always have to be swapped so
* that the representation is litle endian in the file system.
*/
fat_putuint16(&ptr[0], val[1]);
fat_putuint16(&ptr[2], val[0]);
#else
/* Byte-by-byte transfer is still necessary if the address is un-aligned */
/* Byte-by-byte transfer is still necessary because the address may be
* un-aligned.
*/
fat_putuint16(&ptr[0], val[0]);
fat_putuint16(&ptr[2], val[1]);