--- a/HP3562A/__init__.py Tue Dec 18 00:38:33 2007 +0100
+++ b/HP3562A/__init__.py Wed Dec 19 00:19:25 2007 +0100
@@ -15,27 +15,46 @@
import struct
import re
import gpib
+import numpy
########################################
# HP3562A internal binary types decoders
def decode_float(s):
- assert len(s) in [4,8]
- # exponential term
- e = ord(s[-1])
- if e & 0x80:
- e = e - 256
+ if len(s) == 4:
+ i1, i2, e = struct.unpack('>hbb', s)
+ i2 = i2 * 2**(-23)
+ return (i1/32768. + i2)*2**e
+ else:
+ i1, i2, i3, i4, e = struct.unpack('>hhhbb', s)
+ if i2 < 0:
+ i2 = (i2+32768.)*2**(-15)
+ else:
+ i2 = i2*2**(-15)
+ if i3 < 0:
+ i3 = (i3+32768.)*2**(-30)
+ else:
+ i3 = i3*2**(-15)
+ i4 = i4 * 2**(-38)
+ return (i1+i2+i3+i4)*2**(e-15)
+
+# def decode_float(s):
+# assert len(s) in [4,8]
+# # exponential term
+# e = ord(s[-1])
+# if e & 0x80:
+# e = e - 256
- # mantissa
- m = [ord(x) for x in s[:-1]]
- M = 0.
- for i in range(len(s)-1):
- #M += m[i]<<(i*8)
- M += float(m[i])/2**((i+1)*8)
- # XXX how do we deal negative numbers?
- #if m[0] & 0x80:
- # M = M - 2^(len(s))
- return M * 2**(e+1)
+# # mantissa
+# m = [ord(x) for x in s[:-1]]
+# M = 0.
+# for i in range(len(s)-1):
+# #M += m[i]<<(i*8)
+# M += float(m[i])/2**((i+1)*8)
+# # XXX how do we deal negative numbers?
+# #if m[0] & 0x80:
+# # M = M - 2^(len(s))
+# return M * 2**(e+1)
def decode_string(s):
nb = ord(s[0])
@@ -59,6 +78,8 @@
for row in head_struct:
key = row[0]
typ = row[1]
+ if typ is None:
+ continue
val = header.get(key, "N/A")
if isinstance(val, basestring):
val = repr(val)
@@ -83,23 +104,31 @@
fmt = "%%-%ds %%-%ds"%(maxk, maxv)
w = maxk+maxv+4
ncols = columns/w
- nrows = len(todisp)/ncols
+ if ncols:
+ nrows = len(todisp)/ncols
+ else:
+ nrows = len(todisp)
res = ""
for i in range(nrows):
res += "| ".join([fmt%todisp[j*nrows+i] for j in range(ncols)]) + "\n"
return res
-def decode_header(data, header_struct):
+def decode_header(data, header_struct, idx=0):
d = data
- typ = d[:2]
- assert typ == "#A"
-
- totlen = struct.unpack('>h', d[2:4])[0]
- idx = 4
+ if d[idx:].startswith('#'):
+ # we have a preliminary header here...
+ typ = d[idx:idx+2]
+ assert typ == "#A"
+ idx += 2
+ totlen = struct.unpack('>h', d[idx:idx+2])[0]
+ idx += 2
tt=0
header = {}
for i, (nam, dtype, fmt, nbytes) in enumerate(header_struct):
- if dtype == str:
+ if dtype is None:
+ idx += nbytes
+ continue
+ elif dtype == str:
val = decode_string(d[idx:])
else:
if fmt:
@@ -114,6 +143,14 @@
idx += nbytes
return header, idx
+def read_trace(data, idx, nelts):
+ assert len(data[idx:]) >= (nelts*4), "data[idx:] is too small (%s for %s)"%(len(data[idx:]), (nelts*4))
+ resu = []
+ for i in range(nelts):
+ resu.append(decode_float(data[idx: idx+4]))
+ idx += 4
+ return numpy.array(resu, dtype=float)
+
#####################
# HP3562A constants
