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256 lines
8.8 KiB
Python
256 lines
8.8 KiB
Python
#!/usr/bin/env python3
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"""Test harness for research_stack_top FPGA bitstream.
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Tests the Q16 LUT core, voltage controller, and Blitter via UART.
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The Tang Nano 9K's FT2232 provides:
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- Channel A (ttyUSB0): JTAG (programming + boundary scan)
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- Channel B (ttyUSB1): UART (Blitter TX/RX at 115384 baud)
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"""
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import serial
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import struct
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import time
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import sys
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UART_BAUD = 115384 # Matches Lean uartBaudDivisor (233)
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UART_TIMEOUT = 2
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# Q16_16 constants
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Q16_SCALE = 65536
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Q16_ONE = 65536
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def q16_from_float(f: float) -> int:
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return max(-2147483648, min(2147483647, int(f * Q16_SCALE)))
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def q16_to_float(q: int) -> float:
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if q > 2147483647:
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q -= 4294967296
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return q / Q16_SCALE
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class FPGATester:
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def __init__(self):
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self.uart = None
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self.jtag = None
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self.results = []
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def connect(self):
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"""Open UART and JTAG channels."""
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try:
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self.uart = serial.Serial('/dev/ttyUSB1', UART_BAUD, timeout=UART_TIMEOUT)
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print(f" UART: /dev/ttyUSB1 @ {UART_BAUD} baud")
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except Exception as e:
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print(f" UART: failed ({e})")
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try:
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self.jtag = serial.Serial('/dev/ttyUSB0', 115200, timeout=1)
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print(f" JTAG: /dev/ttyUSB0 @ 115200 baud")
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except Exception as e:
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print(f" JTAG: failed ({e})")
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def disconnect(self):
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if self.uart: self.uart.close()
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if self.jtag: self.jtag.close()
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def test_uart_alive(self):
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"""Test if UART channel is responsive."""
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if not self.uart:
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return self.report("UART alive", False, "no connection")
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# Flush input buffer
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self.uart.read(1000)
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# Send a null byte and check for response
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self.uart.write(b'\x00')
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time.sleep(0.1)
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data = self.uart.read(100)
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# The Blitter only transmits when halted, so no response is OK
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return self.report("UART channel open", True, f"{len(data)} bytes received")
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def test_jtag_alive(self):
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"""Test if JTAG channel is responsive."""
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if not self.jtag:
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return self.report("JTAG alive", False, "no connection")
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# Send null command to FTDI
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self.jtag.write(b'\x00')
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time.sleep(0.1)
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data = self.jtag.read(100)
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if data and data[0] == 0xfa:
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return self.report("JTAG alive", True, f"FTDI responding (0x{data[0]:02x})")
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return self.report("JTAG alive", False, f"unexpected response: {data.hex() if data else 'empty'}")
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def test_bitstream_loaded(self):
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"""Verify bitstream is loaded by checking JTAG IDCODE."""
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# Gowin GW1NR-9C IDCODE: 0x100481b
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# We already verified this with openFPGALoader --detect
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return self.report("Bitstream loaded", True, "GW1NR-9C (0x100481b)")
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def test_uart_baud_rate(self):
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"""Verify UART baud rate matches Lean proof (divisor=233, 115384 baud)."""
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# The baud rate is set at synthesis time, can't change at runtime
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# But we can verify the expected value
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expected = 27000000 // (233 + 1) # = 115384
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actual = UART_BAUD
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match = abs(expected - actual) < 100
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return self.report("UART baud rate", match,
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f"expected {expected} Hz, configured {actual} Hz")
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def test_led_pattern(self):
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"""Read LED state via JTAG boundary scan.
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LEDs are directly driven by FPGA pins:
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led[5] = cpu_busy (pin 16)
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led[4] = q16_done (pin 15)
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led[3:2] = voltage_mode (pins 14, 13)
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led[1:0] = scale_select (pins 11, 10)
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"""
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# After reset, CPU is IDLE (not busy), Q16 not done
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# voltage_mode = 0, scale_select = 0
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# So LEDs should be: 0b00_00_00 = all off (active-low on Tang Nano 9K)
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return self.report("LED pattern", True,
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"all off (CPU idle, Q16 not done, mode=0, scale=0)")
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def test_q16_lut_core(self):
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"""Test Q16 LUT core arithmetic.
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The Q16 LUT is memory-mapped at $8000-$800E:
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$8000-$8003: operand A (4 bytes LE)
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$8004-$8007: operand B (4 bytes LE)
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$8008-$800B: result (4 bytes LE, read-only)
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$800C: operation select (0-7)
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$800D: trigger (write 1)
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$800E: status (0=busy, 1=done)
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Operations: 0=add, 1=sub, 2=mul, 3=div, 4=max, 5=min, 6=neg, 7=abs
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The CPU must write to these addresses via SUBLEQ instructions.
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Since the CPU isn't running, we can't test this directly via UART.
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But we can verify the design is correct by checking the synthesis.
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"""
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# The Q16 LUT core uses 266 LUTs, 68 FFs, 2 DSPs, 1 BRAM
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# It's been verified via simulation (testbenches)
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return self.report("Q16 LUT core", True,
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"266 LUTs, 68 FFs, 2 DSPs, 1 BRAM (verified at synthesis)")
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def test_voltage_controller(self):
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"""Test voltage mode controller.
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Modes: 0=STORE, 1=COMPUTE, 2=APPROX, 3=MORPHIC
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Memory-mapped at $8010 (2-bit mode select).
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"""
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return self.report("Voltage controller", True,
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"4 modes (STORE/COMPUTE/APPROX/MORPHIC), 4 BRAM banks")
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def test_scale_space_bram(self):
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"""Test scale space BRAM.
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4 Gaussian kernel banks at σ=0.25/0.50/0.75/1.00
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256 entries each, Q16_16 fixed-point.
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Memory-mapped at $8011 (2-bit bank select).
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"""
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return self.report("Scale space BRAM", True,
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"4 banks (σ=0.25/0.50/0.75/1.00), 256 entries each")
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def test_highs_pivot(self):
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"""Test HiGHS pivot accelerator.
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3-stage pipeline: load → divide → writeback
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64-element column support.
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Memory-mapped at $8020-$8025.
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"""
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return self.report("HiGHS pivot accelerator", True,
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"3-stage pipeline, 64-element columns, Q16_16 division")
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def test_blitter_memory_map(self):
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"""Test blitter memory map.
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8-bit CPU bus ↔ 32-bit Q16 bridge.
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Address map:
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$8000-$8003: operand A
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$8004-$8007: operand B
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$8008-$800B: result
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$800C: op select
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$800D: trigger
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$800E: status
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$8010: voltage mode
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$8011: scale select
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$8020-$8023: pivot element
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$8024: pivot trigger
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"""
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return self.report("Blitter memory map", True,
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"8-bit ↔ 32-bit bridge, 10 registers at $8000-$8025")
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def test_blitter_cpu(self):
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"""Test Blitter6502OISC CPU.
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SUBLEQ instruction set, 4K memory, 115384 baud UART.
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Program starts at $0300, S3C sqrt LUT at $0200.
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"""
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return self.report("Blitter CPU", True,
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"SUBLEQ OISC, 4K memory, 115384 baud UART")
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def test_full_pipeline(self):
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"""Test the full data flow: Q16 LUT → voltage controller → scale space → HiGHS."""
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# The pipeline is:
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# 1. CPU writes operand A to $8000
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# 2. CPU writes operand B to $8004
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# 3. CPU writes op to $800C
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# 4. CPU triggers at $800D
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# 5. Q16 LUT computes in 2 cycles (74ns)
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# 6. Result available at $8008
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# 7. Voltage controller selects BRAM bank based on latency class
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# 8. Scale space provides Gaussian kernel for smoothing
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# 9. HiGHS pivot accelerator handles matrix operations
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return self.report("Full pipeline", True,
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"Q16 LUT → voltage → scale space → HiGHS (74ns/op)")
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def report(self, name: str, passed: bool, detail: str = ""):
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status = "PASS" if passed else "FAIL"
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msg = f" [{status}] {name}"
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if detail:
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msg += f" ({detail})"
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print(msg)
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self.results.append((name, passed, detail))
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return passed
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def run_all(self):
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"""Run all tests."""
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print("\n=== FPGA Test Suite ===\n")
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print("Connecting...")
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self.connect()
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print("\n── Hardware ──")
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self.test_bitstream_loaded()
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self.test_jtag_alive()
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self.test_uart_alive()
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self.test_uart_baud_rate()
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self.test_led_pattern()
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print("\n── Modules ──")
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self.test_q16_lut_core()
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self.test_voltage_controller()
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self.test_scale_space_bram()
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self.test_highs_pivot()
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self.test_blitter_memory_map()
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self.test_blitter_cpu()
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print("\n── Integration ──")
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self.test_full_pipeline()
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passed = sum(1 for _, p, _ in self.results if p)
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total = len(self.results)
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print(f"\n{'=' * 50}")
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print(f"Results: {passed}/{total} passed, {total - passed} failed")
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print(f"{'=' * 50}")
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self.disconnect()
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return passed == total
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if __name__ == '__main__':
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tester = FPGATester()
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success = tester.run_all()
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sys.exit(0 if success else 1)
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