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PCGen 5.13.13 (Development branch)
04-10-2008
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emulate_branch(3) Library Functions Manual emulate_branch(3) Name emulate_branch, execute_branch - branch emulation Syntax #include <signal.h> emulate_branch(scp, branch_instruction) struct sigcontext *scp; unsigned long branch_instruction; execute_branch(branch_instruction) unsigned long branch_instruction; Description The function is passed a signal context structure and a branch instruction. It emulates the branch based on the register values in the signal context structure. It modifies the value of the program counter in the signal context structure (sc_pc) to the target of the branch_instruction. The program counter must initially be pointing at the branch and the register values must be those at the time of the branch. If the branch is not taken the program counter is advanced to point to the instruction after the delay slot (sc_pc += 8). If the branch instruction is a `branch on coprocessor 2' or `branch on coprocessor 3' instruction, calls to execute the branch in data space to determine if it is taken or not. Return Values The function returns a 0 if the branch was emulated successfully. A non-zero value indicates the value passed as a branch instruction was not a branch instruction. The function returns non-zero on taken branches and zero on non-taken branches. Restrictions Since is only intended to be used by it does not check its parameter to see if in fact it is a branch instruction. It is really a stop gap in case a coprocessor is added without the kernel fully supporting it (which is unlikely). See Also cacheflush(2), sigvec(2), signal(3) RISC emulate_branch(3)