# Headless post-script: find instructions that write the GP register and
# report candidate GP base values. Once GP is known, set it as register
# context and re-run analysis so GP-relative data references resolve.
# Run via pyghidra ghidra_launch ... -postScript FindGPInit.py
#@category Analysis

listing = currentProgram.getListing()
reg = currentProgram.getLanguage().getRegisters()
gp_regs = [r for r in reg if r.getName().lower() in ('gp', 'r26', 'r11')]
print('GP candidates: %s' % [r.getName() for r in gp_regs])

it = listing.getInstructions(True)
hits = 0
while it.hasNext() and hits < 80:
    ins = it.next()
    n = ins.getNumOperands()
    for i in range(n):
        try:
            ops = ins.getOpObjects(i)
        except Exception:  # noqa: BLE001
            continue
        for o in ops:
            if hasattr(o, 'getName') and o in gp_regs:
                # operand 0 = destination on NDS32 ALU forms
                if i == 0:
                    print('%s  %s' % (ins.getAddress(), ins))
                    hits += 1
print('total gp-writes shown: %d' % hits)