P3.1: extract FFT code from rt snap (extract_fft.py); decode cplx_mul 0x8440 = in-place elementwise double mult, twiddle loader 0x39b00 stride copy, dispatcher 0x535a70->0x140a10/70->jumptable[0x1826159a0]=4; implement cplx_mul_scalar_inplace

handoff/extract_fft.py

@@ -0,0 +1,56 @@
+#!/usr/bin/env python3
+"""extract_fft.py — extract FFT-related code regions from the rt snap into raw bins."""
+import struct, mmap, os
+
+SNAP = '/tmp/snap_rt.bin'
+OUT = '/tmp/fft/'
+
+# (name, addr, size)
+TARGETS = [
+    ('cplx_mul_8440', 0x180008440, 0x80),
+    ('cplx_mul_kernel_c440', 0x18000c440, 0x100),
+    ('stage_bfc0', 0x18000bfc0, 0x600),
+    ('stage_c5e0', 0x18000c5e0, 0x600),
+    ('twiddle_loader_39b00', 0x180039b00, 0x400),
+    ('plan_gen_2f980', 0x18002f980, 0x1200),
+    ('dispatcher_535a70', 0x180535a70, 0x100),
+    ('scalar_140a10', 0x180140a10, 0x200),
+    ('vector_140a70', 0x180140a70, 0x200),
+    ('fft_kernel_a5a0', 0x18001a5a0, 0x100),
+]
+
+
+def main():
+    os.makedirs(OUT, exist_ok=True)
+    fd = os.open(SNAP, os.O_RDONLY)
+    sz = os.fstat(fd).st_size
+    mm = mmap.mmap(fd, 0, access=mmap.ACCESS_READ)
+    # parse region index once
+    regs = []
+    i = 0
+    while i + 16 <= sz:
+        lo, n = struct.unpack_from('<QQ', mm, i)
+        regs.append((lo, i + 16, n))  # (addr, data_off, size)
+        i += 16 + n
+    regs.sort()
+
+    def readabs(addr, n):
+        for lo, off, rn in regs:
+            if lo <= addr < lo + rn and addr - lo + n <= rn:
+                return mm[off + (addr - lo): off + (addr - lo) + n]
+        return None
+
+    for name, addr, n in TARGETS:
+        b = readabs(addr, n)
+        if b:
+            with open(os.path.join(OUT, name + '.bin'), 'wb') as f:
+                f.write(b)
+            print('%-28s 0x%x %d bytes OK' % (name, addr, len(b)))
+        else:
+            print('%-28s 0x%x MISSING' % (name, addr))
+    mm.close()
+    os.close(fd)
+
+
+if __name__ == '__main__':
+    main()