I have following code but find that x and y are the same value on the debugger. viewing ARM assembly review that the memcpy use same string address. #define A "\xA0\x00\x01" #define B "\xA0\x00\x02" memcpy(x, A, sizeof(A)-1); memcpy(y, B, sizeof(B)-1); If I change #define A "\xA0\x01\x01" #define B "\xA0\x02\x02" it will be OK. Tam
They are both NUL-terminated after '\xA0'.
My problem is following two definitions are the same according to the compiler.
#define A "\xA0\x00\x01" #define B "\xA0\x00\x02"
if( memcmp( in_buffer, A, sizeof(A))==0) { handle_cmd_A(); } else if( memcmp( in_buffer, B, sizeof(B))==0) { handle_cmd_B(); } else { ... }
"My problem is following two definitions are the same according to the compiler." No - not according to the Compiler. What people are talking about is that the way that the Debugger displays the data. The suggestion is that the Debugger is assuming that your data is supposed to be a null-terminated 'C' string, and so is terminating its display of the string at the first null. You need to inspect the memory directly to be sure of what's going on.
An alternative might be:
#define HEADER_0 0x0A #define HEADER_1 0x00 #define MSG_TYPE_1 0x01 #define MSG_TYPE_2 0x02 if( (in_buffer[0]==HEADER_0) && (in_buffer[1]==HEADER_1) ) { // We have detected the start of a header // Now check which type of message it is if( in_buffer[2]==MSG_TYPE_1 ) { // It is a Type-1 message } else if( in_buffer[2]==MSG_TYPE_2 ) { // It is a Type-2 message } }
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