#!/usr/bin/env python3
"""Clock EXACTLY the requested byte count, the way the GC driver does."""
import time, collections
import RPi.GPIO as GPIO
CLK, MOSI, MISO, CS = 11, 10, 9, 8
GPIO.setmode(GPIO.BCM); GPIO.setwarnings(False)
GPIO.setup(CLK, GPIO.OUT, initial=1); GPIO.setup(MOSI, GPIO.OUT, initial=0)
GPIO.setup(CS, GPIO.OUT, initial=1);  GPIO.setup(MISO, GPIO.IN)

def xfer(b):
    r = 0
    for i in range(7, -1, -1):
        GPIO.output(MOSI, (b >> i) & 1)
        GPIO.output(CLK, 0)
        r = (r << 1) | GPIO.input(MISO)
        GPIO.output(CLK, 1)
    return r

def read(addr, n, gap=0.005, idle=0.010):
    GPIO.output(CS, 0); GPIO.output(CLK, 1); time.sleep(0.0005)
    xfer((addr >> 6) & 0x7F); xfer(((addr & 0x3F) << 2) | ((n - 1) & 3))
    time.sleep(gap)
    out = [xfer(0x00) for _ in range(n)]      # EXACTLY n bytes, no more
    GPIO.output(CS, 1); time.sleep(idle)
    return out

def trial(tag, addr, n, want, reps=21, idle=0.010):
    hits = collections.Counter(); ok = 0
    seq = []
    for _ in range(reps):
        r = read(addr, n, idle=idle)
        hits[" ".join("%02x" % x for x in r)] += 1
        good = r == want
        ok += good
        seq.append("." if good else "x")
    print(f"  {tag:<34} {ok:>2}/{reps}   {''.join(seq)}")
    for pat, cnt in hits.most_common(3):
        print(f"        {cnt:>3}x  {pat}")

print("=== exact-length reads, 10ms idle between transactions ===")
trial("device ID @0x0000 (4B)", 0x0000, 4, [0x04, 0x02, 0x02, 0x00])
trial("NWAYS @0x31 (1B)",       0x31,   1, [0x17])
trial("HIPR  @0x3A (1B)",       0x3A,   1, [0x01])
print()
print("=== same, but 200ms idle (does state decay?) ===")
trial("device ID @0x0000 (4B)", 0x0000, 4, [0x04, 0x02, 0x02, 0x00], reps=9, idle=0.200)
GPIO.cleanup()