From 823357b90906df451402358eda7b995143922496 Mon Sep 17 00:00:00 2001 From: Christian Heller Date: Thu, 15 Aug 2013 17:21:07 +0200 Subject: [PATCH] More comments on readwrite library; some refactoring ideas included. --- src/readwrite.c | 32 +++++++++++++++++++------------- 1 file changed, 19 insertions(+), 13 deletions(-) diff --git a/src/readwrite.c b/src/readwrite.c index 2b6823a..e776ec2 100644 --- a/src/readwrite.c +++ b/src/readwrite.c @@ -6,7 +6,15 @@ -/* Read/write "x" from/to "file" as bigendian representation of "size" bits. */ +/* Read/write "x" from/to "file" as bigendian representation of "size" bits. + * Only multiples of 8 allowed for "size". On failure, return 1, else 0. + * + * As of of now, all other read/write functions build on top of these. TODO: + * Consider externing these so-far internal functions and dropping the + * interfaces to them, instead relying on their internal validity checks. + * (Usage of padded memory copies instead of directly manipulating * x as is + * done in read_uint* would need to be added, though.) + */ static uint8_t read_uintX_bigendian(FILE * file, uint32_t * x, uint8_t size); static uint8_t write_uintX_bigendian(FILE * file, uint32_t x, uint8_t size); @@ -14,10 +22,10 @@ static uint8_t write_uintX_bigendian(FILE * file, uint32_t x, uint8_t size); static uint8_t read_uintX_bigendian(FILE * file, uint32_t * x, uint8_t size) { - if (0 != size % 8) - { - return 1; - } + if (0 != size % 8) /* This bit number validity check is redundant */ + { /* as long as this function is only available */ + return 1; /* through extern interfaces pre-defining the */ + } /* bit number. TODO: Consider dropping it. */ int16_t bitshift = size - 8; * x = 0; @@ -38,10 +46,10 @@ static uint8_t read_uintX_bigendian(FILE * file, uint32_t * x, uint8_t size) static uint8_t write_uintX_bigendian(FILE * file, uint32_t x, uint8_t size) { - if (0 != size % 8) - { - return 1; - } + if (0 != size % 8) /* See comment */ + { /* on identical */ + return 1; /* code block in */ + } /* read_uintX_bigendian(). */ int16_t bitshift = size - 8; for (; bitshift >= 0; bitshift = bitshift - 8) @@ -58,10 +66,8 @@ static uint8_t write_uintX_bigendian(FILE * file, uint32_t x, uint8_t size) extern uint8_t read_uint8(FILE * file, uint8_t * x) { - /* Since read_uintX_bigendian() works on -- and zeroes -- four bytes, work - * on values of fewer bytes corrupts their immediate neighbor bytes. This - * necessitates working on newly acquired separate memory areas (* y), only - * copying the sufficiently small end result to * x. + /* Since read_uintX_bigendian() works on -- and zeroes -- four bytes, direct + * work on values of fewer bytes would corrupt immediate neighbor values. */ uint32_t y = * x; uint8_t err = read_uintX_bigendian(file, &y, 8); -- 2.30.2