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"""Helpers specific to the mapping mode."""
from .stats import stats_from_mapping_mode
def dword(array, index, bitsize=16):
"""Extract a dword value from two words starting at the given index."""
return array[index] | array[index+1] << bitsize
def parse_mapping_buffer(raw):
"""Parse the given mapping buffer and return a (spectrums, statistics) tuple.
Both results are dictionaries of dictionaries, first indexed by pixel,
then channels:
- spectrums: <pixel: <channel: spectrum (1D array)>
- statistics: <pixel: <channel: stats (Stats object)>
"""
spectrums, statistics = {}, {}
# XMAP/Mercury parsing
if raw[1] == 0:
raw = raw[::2]
spectrum_type = 'uint16'
# FalconX parsing
else:
spectrum_type = 'uint32'
# Header advance
header = raw[0:256]
current = 256
# Header parsing
assert header[0] == 0x55aa
assert header[1] == 0xaa55
assert header[2] == 0x100
mapping_mode = header[3]
buffer_index = dword(header, 4)
buffer_id = header[7]
pixel_number = header[8]
starting_pixel = dword(header, 9)
module_serial_number = header[11]
channel_ids = header[12:20:2]
channel_detector_ids = header[13:20:2]
# Checks
assert mapping_mode == 1 # MCA mapping mode
assert starting_pixel == dword(raw, 256+4)
assert buffer_id in (0, 1)
# Unused information, should we do something with it?
buffer_index, module_serial_number, channel_detector_ids
# Iterate over pixels
for _ in range(pixel_number):
# Pixel header advance
pixel_header = raw[current:current+256]
current += 256
# Pixel header parsing
assert pixel_header[0] == 0x33cc
assert pixel_header[1] == 0xcc33
assert pixel_header[2] == 0x100
assert pixel_header[3] == mapping_mode
pixel = dword(pixel_header, 4)
total_size = dword(pixel_header, 6)
sizes = pixel_header[8:12]
# Statistics block
stats_block = [
[dword(pixel_header, 32 + 8 * i + 2 * j) for j in range(4)]
for i in range(4)]
# Iterate over channels
spectrums[pixel] = {}
statistics[pixel] = {}
remaining = total_size - 256
for index, channel_id, size in zip(range(4), channel_ids, sizes):
# Update remaining size
assert remaining >= 0
if remaining == 0:
break
remaining -= size
# Sectrum Advance
spectrum = raw[current:current+size]
spectrum.dtype = spectrum_type
current += size
# Discard garbage
if channel_id in spectrums[pixel]:
continue
# Set data
stats = stats_from_mapping_mode(stats_block[index])
spectrums[pixel][channel_id] = spectrum
statistics[pixel][channel_id] = stats
# Checks
assert remaining == 0
# Return results
return spectrums, statistics
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