mewin/libpng
1
0
Fork 0
mirror of https://git.code.sf.net/p/libpng/code.git synced 2025-07-10 18:04:09 +02:00
Code Issues Projects Releases Wiki Activity

Remove top-level const from function-scope variables

Browse Source 
As per the const correctness rules, top-level const-ness of data
in automatic scopes does not propagate outside of these scopes
(unlike const-ness at lower levels, such as pointers to const data).

Previously, const was used liberally, but inconsistently across the
libpng codebase. Using const wherever applicable is not incorrect.
However, _consistent_ use of const is difficult to maintain in such
conditions.

In conclusion, we shall continue to use const only where doing so is
strictly necessary:

1. If a function guarantees that it will not modify an argument
   passed by pointer, the corresponding function parameter should be
   a pointer-to-const (const T *).

2. Static data should not be modified, therefore it should be const.

Reference:
Google C++ Style Guide
https://google.github.io/styleguide/cppguide.html#Use_of_const
This commit is contained in:
Cosmin Truta
2018-08-18 22:47:16 -04:00
parent 1ef8882814
commit ceb327789b
22 changed files with 196 additions and 205 deletions
Download Patch File Download Diff File Expand all files Collapse all files

16
png.c
View File

@@ -3970,18 +3970,18 @@ png_gamma_correct(png_structrp png_ptr, unsigned int value,
*/
static void
png_build_16bit_table(png_structrp png_ptr, png_uint_16pp *ptable,
const unsigned int shift, const png_fixed_point gamma_val)
unsigned int shift, png_fixed_point gamma_val)
{
/* Various values derived from 'shift': */
const unsigned int num = 1U << (8U - shift);
unsigned int num = 1U << (8U - shift);
#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
/* CSE the division and work round wacky GCC warnings (see the comments
* in png_gamma_8bit_correct for where these come from.)
*/
const double fmax = 1./(((png_int_32)1 << (16U - shift))-1);
#endif
const unsigned int max = (1U << (16U - shift))-1U;
const unsigned int max_by_2 = 1U << (15U-shift);
unsigned int max = (1U << (16U - shift))-1U;
unsigned int max_by_2 = 1U << (15U-shift);
unsigned int i;
png_uint_16pp table = *ptable =
@@ -4047,10 +4047,10 @@ png_build_16bit_table(png_structrp png_ptr, png_uint_16pp *ptable,
*/
static void
png_build_16to8_table(png_structrp png_ptr, png_uint_16pp *ptable,
const unsigned int shift, const png_fixed_point gamma_val)
unsigned int shift, png_fixed_point gamma_val)
{
const unsigned int num = 1U << (8U - shift);
const unsigned int max = (1U << (16U - shift))-1U;
unsigned int num = 1U << (8U - shift);
unsigned int max = (1U << (16U - shift))-1U;
unsigned int i;
png_uint_32 last;
@@ -4115,7 +4115,7 @@ png_build_16to8_table(png_structrp png_ptr, png_uint_16pp *ptable,
*/
static void
png_build_8bit_table(png_structrp png_ptr, png_bytepp ptable,
const png_fixed_point gamma_val)
png_fixed_point gamma_val)
{
unsigned int i;
png_bytep table = *ptable = (png_bytep)png_malloc(png_ptr, 256);