130 lines
3.9 KiB
Python
130 lines
3.9 KiB
Python
"""Sometimes we want to extract a specific bit for
|
|
comparison or testing"""
|
|
"""Shifting a register."""
|
|
import rp2pio
|
|
import adafruit_pioasm
|
|
import array
|
|
|
|
def scenario(test_data, bit_to_extract, expected):
|
|
program = f"""
|
|
.program extract_bit
|
|
set y, {test_data} ; set a value in y
|
|
|
|
; extract - by shifting
|
|
in null, 32 ; clear the isr
|
|
in y, {bit_to_extract + 1} ; get n bits
|
|
|
|
; debug isr
|
|
mov x, isr ; preserve isr - pushing destroys it
|
|
push noblock
|
|
mov isr, x ; restore isr
|
|
; done debug
|
|
|
|
in null, 31 ; Shift off all but last bit (leaving it)
|
|
|
|
; debug isr
|
|
mov x, isr ; preserve isr - pushing destroys it
|
|
push noblock
|
|
mov isr, x ; restore isr
|
|
; done debug
|
|
|
|
mov y, isr ; reverse the isr back into y
|
|
|
|
; send y to fifo
|
|
mov isr, y
|
|
push noblock ; and use PUSH to put it on the receive FIFO
|
|
"""
|
|
assembled = adafruit_pioasm.assemble(program)
|
|
|
|
## set up a statemachine
|
|
with rp2pio.StateMachine(
|
|
assembled,
|
|
frequency=2000,
|
|
) as sm:
|
|
buffer = array.array('I', [0])
|
|
|
|
print("source bits: {0} 0b{0:032b} 0x{0:x}".format(test_data))
|
|
sm.readinto(buffer)
|
|
print("isr mid: {0} 0b{0:032b} 0x{0:x}".format(buffer[0]))
|
|
sm.readinto(buffer)
|
|
print("isr after shift off: {0} 0b{0:032b} 0x{0:x}".format(buffer[0]))
|
|
sm.readinto(buffer)
|
|
print("Y bit extracted: {0} 0b{0:032b} 0x{0:x}".format(buffer[0]))
|
|
if buffer[0] != expected:
|
|
print("Didn't get what I expected")
|
|
print("Y bit expected: {0} 0b{0:032b} 0x{0:x}".format(expected))
|
|
print("")
|
|
|
|
def pull_scenario(test_data, bit_to_extract, expected):
|
|
program = f"""
|
|
.program extract_bit_pull
|
|
pull block ; pull data
|
|
mov y, osr
|
|
|
|
; extract - by shifting
|
|
in null, 32 ; clear the isr
|
|
in y, {bit_to_extract + 1} ; get n bits
|
|
|
|
; debug isr
|
|
mov x, isr ; preserve isr - pushing destroys it
|
|
push noblock
|
|
mov isr, x ; restore isr
|
|
; done debug
|
|
|
|
in null, 31 ; Shift off all but last bit (leaving it)
|
|
|
|
; debug isr
|
|
mov x, isr ; preserve isr - pushing destroys it
|
|
push noblock
|
|
mov isr, x ; restore isr
|
|
; done debug
|
|
|
|
mov y, isr ; reverse the isr back into y
|
|
|
|
; send y to fifo
|
|
mov isr, y
|
|
push noblock ; and use PUSH to put it on the receive FIFO
|
|
"""
|
|
assembled = adafruit_pioasm.assemble(program)
|
|
|
|
## set up a statemachine
|
|
with rp2pio.StateMachine(
|
|
assembled,
|
|
frequency=2000,
|
|
) as sm:
|
|
sm.write(array.array('I', [test_data]))
|
|
buffer = array.array('I', [0])
|
|
|
|
print("source bits: {0} 0b{0:032b} 0x{0:x}".format(test_data))
|
|
sm.readinto(buffer)
|
|
print("isr mid: {0} 0b{0:032b} 0x{0:x}".format(buffer[0]))
|
|
sm.readinto(buffer)
|
|
print("isr after shift off: {0} 0b{0:032b} 0x{0:x}".format(buffer[0]))
|
|
sm.readinto(buffer)
|
|
print("Y bit extracted: {0} 0b{0:032b} 0x{0:x}".format(buffer[0]))
|
|
if buffer[0] != expected:
|
|
print("Didn't get what I expected")
|
|
print("Y bit expected: {0} 0b{0:032b} 0x{0:x}".format(expected))
|
|
print("")
|
|
|
|
scenario(0b101, 1, 0)
|
|
scenario(0b110, 1, 1)
|
|
scenario(0b010, 1, 1)
|
|
scenario(0b100, 2, 1)
|
|
scenario(0b011, 2, 0)
|
|
scenario(0b1011, 3, 1)
|
|
scenario(0b1010, 3, 1)
|
|
scenario(0b1000, 3, 1)
|
|
scenario(0b0111, 3, 0)
|
|
# bit I want
|
|
# v
|
|
pull_scenario(0b10101000_00000000_00000000_00000000, 29, 1)
|
|
pull_scenario(0b11011000_00000000_00000000_00000000, 29, 0)
|
|
# v
|
|
pull_scenario(0b01011000_00000000_00000000_00000000, 30, 1)
|
|
pull_scenario(0b10111000_00000000_00000000_00000000, 30, 0)
|
|
# v
|
|
pull_scenario(0b10111000_00000000_00000000_00000000, 31, 1)
|
|
pull_scenario(0b01111000_00000000_00000000_00000000, 31, 0)
|
|
|