Multiple definition [...] first define here

Question

I'm writing a H264 parser (no OO), but I'm trying to use some modules to organize better the things.

I'm having this problems:

`CMakeFiles/server.dir/mainclass.cpp.o:(.bss+0x0): multiple definition of `I_Macroblock_Modes'  
`CMakeFiles/server.dir/main.cpp.o:(.bss+0x0): first defined here  
`CMakeFiles/server.dir/mainclass.cpp.o:(.bss+0x300): multiple definition of `P_and_SP_macroblock_modes'  
`CMakeFiles/server.dir/main.cpp.o:(.bss+0x300): first defined here  
`CMakeFiles/server.dir/mainclass.cpp.o:(.bss+0x680): multiple definition of `B_Macroblock_Modes' 
`CMakeFiles/server.dir/main.cpp.o:(.bss+0x680): first defined here  
`CMakeFiles/server.dir/thRunAppl.cpp.o:(.bss+0x0): multiple definition of `I_Macroblock_Modes'  
`CMakeFiles/server.dir/main.cpp.o:(.bss+0x0): first defined here  
`CMakeFiles/server.dir/thRunAppl.cpp.o:(.bss+0x300): multiple definition of `P_and_SP_macroblock_modes'  
`CMakeFiles/server.dir/main.cpp.o:(.bss+0x300): first defined here  
`CMakeFiles/server.dir/thRunAppl.cpp.o:(.bss+0x680): multiple definition of `B_Macroblock_Modes'  
`CMakeFiles/server.dir/main.cpp.o:(.bss+0x680): first defined here  
`CMakeFiles/server.dir/h.264parser.cpp.o:(.bss+0x0): multiple definition of `I_Macroblock_Modes'  
`CMakeFiles/server.dir/main.cpp.o:(.bss+0x0): first defined here  
`CMakeFiles/server.dir/h.264parser.cpp.o:(.bss+0x300): multiple definition of `P_and_SP_macroblock_modes'  
`CMakeFiles/server.dir/main.cpp.o:(.bss+0x300): first defined here  
`CMakeFiles/server.dir/h.264parser.cpp.o:(.bss+0x680): multiple definition of `B_Macroblock_Modes'  
`CMakeFiles/server.dir/main.cpp.o:(.bss+0x680): first defined here  
`CMakeFiles/server.dir/moc_mainclass.cxx.o:(.bss+0x0): multiple definition of `I_Macroblock_Modes'
`CMakeFiles/server.dir/main.cpp.o:(.bss+0x0): first defined here
`CMakeFiles/server.dir/moc_mainclass.cxx.o:(.bss+0x300): multiple definition of `P_and_SP_macroblock_modes'
`CMakeFiles/server.dir/main.cpp.o:(.bss+0x300): first defined here
`CMakeFiles/server.dir/moc_mainclass.cxx.o:(.bss+0x680): multiple definition of `B_Macroblock_Modes'
`CMakeFiles/server.dir/main.cpp.o:(.bss+0x680): first defined here
`CMakeFiles/server.dir/moc_thRunAppl.cxx.o:(.bss+0x0): multiple definition of `I_Macroblock_Modes'
`CMakeFiles/server.dir/main.cpp.o:(.bss+0x0): first defined here
`CMakeFiles/server.dir/moc_thRunAppl.cxx.o:(.bss+0x300): multiple definition of `P_and_SP_macroblock_modes'
`CMakeFiles/server.dir/main.cpp.o:(.bss+0x300): first defined here
`CMakeFiles/server.dir/moc_thRunAppl.cxx.o:(.bss+0x680): multiple definition of `B_Macroblock_Modes'
`CMakeFiles/server.dir/main.cpp.o:(.bss+0x680): first defined here
`CMakeFiles/server.dir/h.264parser.cpp.o: In function `MbPartPredMode(int, int)':  
`h.264parser.cpp:(.text+0xf0): undefined reference to `B_macroblockmodes(int, int)'  
`h.264parser.cpp:(.text+0x104): undefined reference to `B_macroblockmodes(int, int)'  
`h.264parser.cpp:(.text+0x111): undefined reference to `I_macroblockmodes(int, int)'  
`h.264parser.cpp:(.text+0x124): undefined reference to `P_and_SP_macroblockmodes(int, int)'  
`h.264parser.cpp:(.text+0x134): undefined reference to `P_and_SP_macroblockmodes(int, int)' 

My scenario is:

macroblocktypes.h. just with defines

macroblocktables.h:

#include "macroblocktypes.h"

int I_Macroblock_Modes[27][7];
int P_and_SP_macroblock_modes[32][7];
int B_Macroblock_Modes[50][7];

int I_macroblockmodes(int line, int column);
int P_and_SP_macroblockmodes(int line, int column);
int B_macroblockmodes(int line, int column);

macroblocktables.cpp, with a array and a function defined like this for each array and function on .h file.

#include "macroblocktables.h"
int I_macroblock_modes[27][7] ={
{0, I_4x4, 0, Intra_4x4, NA, NA, NA},
//If this line was to be commented out, the MbPartPredMode macro would have to be changed
//since it relies on the linear rise of the value in the first column.
//{0,   I_NxN,          1,  Intra_8x8,   NA, NA, NA},
{1, I_16x16_0_0_0, NA, Intra_16x16, 0, 0, 0},
{2, I_16x16_1_0_0, NA, Intra_16x16, 1, 0, 0},
{3, I_16x16_2_0_0, NA, Intra_16x16, 2, 0, 0},
{4, I_16x16_3_0_0, NA, Intra_16x16, 3, 0, 0},
{5, I_16x16_0_1_0, NA, Intra_16x16, 0, 1, 0},
{6, I_16x16_1_1_0, NA, Intra_16x16, 1, 1, 0},
{7, I_16x16_2_1_0, NA, Intra_16x16, 2, 1, 0},
{8, I_16x16_3_1_0, NA, Intra_16x16, 3, 1, 0},
{9, I_16x16_0_2_0, NA, Intra_16x16, 0, 2, 0},
{10, I_16x16_1_2_0, NA, Intra_16x16, 1, 2, 0},
{11, I_16x16_2_2_0, NA, Intra_16x16, 2, 2, 0},
{12, I_16x16_3_2_0, NA, Intra_16x16, 3, 2, 0},
{13, I_16x16_0_0_1, NA, Intra_16x16, 0, 0, 15},
{14, I_16x16_1_0_1, NA, Intra_16x16, 1, 0, 15},
{15, I_16x16_2_0_1, NA, Intra_16x16, 2, 0, 15},
{16, I_16x16_3_0_1, NA, Intra_16x16, 3, 0, 15},
{17, I_16x16_0_1_1, NA, Intra_16x16, 0, 1, 15},
{18, I_16x16_1_1_1, NA, Intra_16x16, 1, 1, 15},
{19, I_16x16_2_1_1, NA, Intra_16x16, 2, 1, 15},
{20, I_16x16_3_1_1, NA, Intra_16x16, 3, 1, 15},
{21, I_16x16_0_2_1, NA, Intra_16x16, 0, 2, 15},
{22, I_16x16_1_2_1, NA, Intra_16x16, 1, 2, 15},
{23, I_16x16_2_2_1, NA, Intra_16x16, 2, 2, 15},
{24, I_16x16_3_2_1, NA, Intra_16x16, 3, 2, 15},
{25, I_PCM, NA, NA, NA, NA, NA}};

int P_and_SP_macroblock_modes[32][7] = {
{0, P_L0_16x16, 1, Pred_L0, NA, 16, 16},
{1, P_L0_L0_16x8, 2, Pred_L0, Pred_L0, 16, 8},
{2, P_L0_L0_8x16, 2, Pred_L0, Pred_L0, 8, 16},
{3, P_8x8, 4, NA, NA, 8, 8},
{4, P_8x8ref0, 4, NA, NA, 8, 8},
{0, I_4x4, 0, Intra_4x4, NA, NA, NA},
{1, I_16x16_0_0_0, NA, Intra_16x16, 0, 0, 0},
{2, I_16x16_1_0_0, NA, Intra_16x16, 1, 0, 0},
{3, I_16x16_2_0_0, NA, Intra_16x16, 2, 0, 0},
{4, I_16x16_3_0_0, NA, Intra_16x16, 3, 0, 0},
{5, I_16x16_0_1_0, NA, Intra_16x16, 0, 1, 0},
{6, I_16x16_1_1_0, NA, Intra_16x16, 1, 1, 0},
{7, I_16x16_2_1_0, NA, Intra_16x16, 2, 1, 0},
{8, I_16x16_3_1_0, NA, Intra_16x16, 3, 1, 0},
{9, I_16x16_0_2_0, NA, Intra_16x16, 0, 2, 0},
{10, I_16x16_1_2_0, NA, Intra_16x16, 1, 2, 0},
{11, I_16x16_2_2_0, NA, Intra_16x16, 2, 2, 0},
{12, I_16x16_3_2_0, NA, Intra_16x16, 3, 2, 0},
{13, I_16x16_0_0_1, NA, Intra_16x16, 0, 0, 15},
{14, I_16x16_1_0_1, NA, Intra_16x16, 1, 0, 15},
{15, I_16x16_2_0_1, NA, Intra_16x16, 2, 0, 15},
{16, I_16x16_3_0_1, NA, Intra_16x16, 3, 0, 15},
{17, I_16x16_0_1_1, NA, Intra_16x16, 0, 1, 15},
{18, I_16x16_1_1_1, NA, Intra_16x16, 1, 1, 15},
{19, I_16x16_2_1_1, NA, Intra_16x16, 2, 1, 15},
{20, I_16x16_3_1_1, NA, Intra_16x16, 3, 1, 15},
{21, I_16x16_0_2_1, NA, Intra_16x16, 0, 2, 15},
{22, I_16x16_1_2_1, NA, Intra_16x16, 1, 2, 15},
{23, I_16x16_2_2_1, NA, Intra_16x16, 2, 2, 15},
{24, I_16x16_3_2_1, NA, Intra_16x16, 3, 2, 15},
{25, I_PCM, NA, NA, NA, NA, NA},
{NA, P_Skip, 1, Pred_L0, NA, 16, 16}};

int B_macroblock_modes[50][7] = {
{0, B_Direct_16x16, NA, Direct, NA, 8, 8},
{1, B_L0_16x16, 1, Pred_L0, NA, 16, 16},
{2, B_L1_16x16, 1, Pred_L1, NA, 16, 16},
{3, B_Bi_16x16, 1, BiPred, NA, 16, 16},
{4, B_L0_L0_16x8, 2, Pred_L0, Pred_L0, 16, 8},
{5, B_L0_L0_8x16, 2, Pred_L0, Pred_L0, 8, 16},
{6, B_L1_L1_16x8, 2, Pred_L1, Pred_L1, 16, 8},
{7, B_L1_L1_8x16, 2, Pred_L1, Pred_L1, 8, 16},
{8, B_L0_L1_16x8, 2, Pred_L0, Pred_L1, 16, 8},
{9, B_L0_L1_8x16, 2, Pred_L0, Pred_L1, 8, 16},
{10, B_L1_L0_16x8, 2, Pred_L1, Pred_L0, 16, 8},
{11, B_L1_L0_8x16, 2, Pred_L1, Pred_L0, 8, 16},
{12, B_L0_Bi_16x8, 2, Pred_L0, BiPred, 16, 8},
{13, B_L0_Bi_8x16, 2, Pred_L0, BiPred, 8, 16},
{14, B_L1_Bi_16x8, 2, Pred_L1, BiPred, 16, 8},
{15, B_L1_Bi_8x16, 2, Pred_L1, BiPred, 8, 16},
{16, B_Bi_L0_16x8, 2, BiPred, Pred_L0, 16, 8},
{17, B_Bi_L0_8x16, 2, BiPred, Pred_L0, 8, 16},
{18, B_Bi_L1_16x8, 2, BiPred, Pred_L1, 16, 8},
{19, B_Bi_L1_8x16, 2, BiPred, Pred_L1, 8, 16},
{20, B_Bi_Bi_16x8, 2, BiPred, BiPred, 16, 8},
{21, B_Bi_Bi_8x16, 2, BiPred, BiPred, 8, 16},
{22, B_8x8, 4, NA, NA, 8, 8},
{0, I_4x4, 0, Intra_4x4, NA, NA, NA},
{1, I_16x16_0_0_0, NA, Intra_16x16, 0, 0, 0},
{2, I_16x16_1_0_0, NA, Intra_16x16, 1, 0, 0},
{3, I_16x16_2_0_0, NA, Intra_16x16, 2, 0, 0},
{4, I_16x16_3_0_0, NA, Intra_16x16, 3, 0, 0},
{5, I_16x16_0_1_0, NA, Intra_16x16, 0, 1, 0},
{6, I_16x16_1_1_0, NA, Intra_16x16, 1, 1, 0},
{7, I_16x16_2_1_0, NA, Intra_16x16, 2, 1, 0},
{8, I_16x16_3_1_0, NA, Intra_16x16, 3, 1, 0},
{9, I_16x16_0_2_0, NA, Intra_16x16, 0, 2, 0},
{10, I_16x16_1_2_0, NA, Intra_16x16, 1, 2, 0},
{11, I_16x16_2_2_0, NA, Intra_16x16, 2, 2, 0},
{12, I_16x16_3_2_0, NA, Intra_16x16, 3, 2, 0},
{13, I_16x16_0_0_1, NA, Intra_16x16, 0, 0, 15},
{14, I_16x16_1_0_1, NA, Intra_16x16, 1, 0, 15},
{15, I_16x16_2_0_1, NA, Intra_16x16, 2, 0, 15},
{16, I_16x16_3_0_1, NA, Intra_16x16, 3, 0, 15},
{17, I_16x16_0_1_1, NA, Intra_16x16, 0, 1, 15},
{18, I_16x16_1_1_1, NA, Intra_16x16, 1, 1, 15},
{19, I_16x16_2_1_1, NA, Intra_16x16, 2, 1, 15},
{20, I_16x16_3_1_1, NA, Intra_16x16, 3, 1, 15},
{21, I_16x16_0_2_1, NA, Intra_16x16, 0, 2, 15},
{22, I_16x16_1_2_1, NA, Intra_16x16, 1, 2, 15},
{23, I_16x16_2_2_1, NA, Intra_16x16, 2, 2, 15},
{24, I_16x16_3_2_1, NA, Intra_16x16, 3, 2, 15},
{25, I_PCM, NA, NA, NA, NA, NA},
{NA, B_Skip, NA, Direct, NA, 8, 8}};

int I_macroblockmodes(int line, int column) {
if (line < 27 && column < 7)
    return I_macroblock_modes[line][column];
else {
    if (line >= 27) {
        return -10000; //line is bigger than the array size
    } else {
        return -20000; //column is bigger than the array size
    }
}}
//Inter prediction slices - Macroblock types
//Defined strictly by norm, page 121.

//(Table 7-13 Macroblock type values 0 to 4 for P and SP slices)
/*
First column:   mb_type
Second column:  Name of mb_type
Third column:   NumMbPart( mb_type )
Fourth column:  MbPartPredMode( mb_type, 0 )
Fifth column:   MbPartPredMode( mb_type, 1 )
Sixth column:   MbPartWidth( mb_type )
Seventh column: MbPartHeight( mb_type )
*/
int P_and_SP_macroblockmodes(int line, int column){
 if (line < 32 && column < 7)
    return P_and_SP_macroblock_modes[line][column];
else {
    if (line >= 32) {
        return -10000; //line is bigger than the array size
    } else {
        return -20000; //column is bigger than the array size
    }
}}



//p94. Table 7-14 – Macroblock type values 0 to 22 for B slices
/*
First column:   mb_type
Second column:  Name of mb_type
Third column:   NumMbPart( mb_type )
Fourth column:  MbPartPredMode( mb_type, 0 )
Fifth column:   MbPartPredMode( mb_type, 1 )
Sixth column:   MbPartWidth( mb_type )
Seventh column: MbPartHeight( mb_type )
 */
int B_macroblockmodes(int line, int column){
 if (line < 50 && column < 7)
    return B_macroblock_modes[line][column];
else {
    if (line >= 50) {
        return -10000; //line is bigger than the array size
    } else {
        return -20000; //column is bigger than the array size
    }
}}

And finally my h.264 files (.cpp and .h). Im including in the .h the macroblocktable.h and macroblocktype.h, and in the h.264.cpp just the h.264.h.

I would like to use the functions from the macroblocktable.cpp in the h.264.cpp.

Thanks in advance

Answer 1

You must keep only the declarations in a .h file, not the definitions, lest you should get any linker errors. These

int I_Macroblock_Modes[27][7];
int P_and_SP_macroblock_modes[32][7];
int B_Macroblock_Modes[50][7];

are definitions, not intuitive as it may seem. Change these to

extern int I_Macroblock_Modes[27][7];
extern int P_and_SP_macroblock_modes[32][7];
extern int B_Macroblock_Modes[50][7];

and you should be fine

Answer 2

It's not "just defines". You are declaring variables inside it, therefore every time that gets included your are redeclaring global variables.

If what you want is to access I_Macroblock_Modes from other .c/.cpp files, in the macroblocktables.h header you should put:

//resides in macroblocktables.cpp
extern int I_Macroblock_Modes[27][7];
extern int P_and_SP_macroblock_modes[32][7];
extern int B_Macroblock_Modes[50][7];

// the rest of it

Because those int arrays are defined in macroblocktables.cpp, right?

In C/C++ everytime you do something like:

int myarray[4];
char mychar;

or more generally

type var_name;

you are telling to the compiler: please allocate on the stack for me, a variable named X that has type T.

when you #include header.h, in the most basic explanation, you are telling the preprocessor: open header.h ctrl+c all of it, and ctrl+v it here. Then that preprocessed source file is fed to your compiler and every time it sees type var_name it will do what i explained above.

Sorry if this is too much info, but I just felt like writing it :P