Guest
#1891635
hello i have an opcode of BNE and i want to know which address it jmb the opcode is 1AFFFFF9 if there is who know how can i understand which address go this brunch
How about telling us which processor you are talking about? Also you could most likely find a description of the opcodes of your processor on the vendor website.
Guest
#1892132
thank you andreas for your reply the processor is DSP TMX320AV7111GFN i think it contain arm7,isn't it? and i want to ask you is all the arm processor has his description of the opcodes??
Guest
#1892158
the processor is ARM7TDMI
http://www.ece.wisc.edu/~morrow/ECE353/arm7tdmi_instruction_set_reference.pdf 1AFFFFF9 means 1 = Condition: not equal A = Branch (Link = 0) FFFFF9 = offset Branch if not equal PC := PC + (offset << 2); This branch can initiate a jump in negative direction to an address that is 7 instructions or 28 bytes ahead.
Guest
#1894040
thank you very much Peter Can you give me an example to Understand more ,please
Guest
#1894555
what does you mean about negative direction
The offset is given in two's complement to encode positive and negative numbers http://en.wikipedia.org/wiki/Two%27s_complement This is because it is a relative jump that can jump forward and backwards. So the offset is the number of instructions to jump (from the current position of the program counter), which can be positive to jump in forward direction or negative to jump in reverse direction. An offset of FFFFF9 (which is -7 in two's complement) means, that a jump from the current position to a position that is 7 instructions earlier is performed.
Guest
#1898377
thank you very muck Peter