Bug #759: undefined behaviour warning in ijg JPEG code - DCMTK - OFFIS DCMTK and DICOM Projects

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Bug #759

closed

undefined behaviour warning in ijg JPEG code

Added by Marco Eichelberg over 8 years ago. Updated over 5 years ago.

Status:

Closed

Priority:

Normal

Assignee:

Category:

Target version:

Start date:

2017-06-21

Due date:

% Done:

100%

Estimated time:

Module:

dcmjpeg

Operating System:

Compiler:

Description

The warning is reported by gcc with option -Waggressive-loop-optimizations and seems to only affect the 16-bit version of the JPEG codec:

libijg16/jccolor.c:118:65: warning: iteration 65535u invokes undefined behavior [-Waggressive-loop-optimizations]

     rgb_ycc_tab[i+B_CB_OFF] = FIX(0.50000) * i    + CBCR_OFFSET + ONE_HALF-1;
                                                                 ^
libijg16/jdmerge.c:108:38: warning: iteration 9396u invokes undefined behavior [-Waggressive-loop-optimizations]

             RIGHT_SHIFT(FIX(1.40200) * x + ONE_HALF, SCALEBITS);