Mercurial > pygpibtoolkit / file comparison
comparison: HP3562A/__init__.py
HP3562A/__init__.py
- changeset 14
- 07e2cbf140df
- parent 13
- 78e3e839658b
- child 15
- b930440af354
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| 13:78e3e839658b | 14:07e2cbf140df |
|---|---|
| 10 | 10 |
| 11 Constants | 11 Constants |
| 12 --------- | 12 --------- |
| 13 | 13 |
| 14 """ | 14 """ |
| 15 import struct | |
| 16 import gpib | |
| 15 | 17 |
| 16 from gpib import gpib | 18 ######################################## |
| 19 # HP3562A internal binary types decoders | |
| 20 | |
| 21 def decode_float(s): | |
| 22 assert len(s) in [4,8] | |
| 23 # exponential term | |
| 24 e = ord(s[-1]) | |
| 25 if e & 0x80: | |
| 26 e = e - 256 | |
| 27 | |
| 28 # mantissa | |
| 29 m = [ord(x) for x in s[:-1]] | |
| 30 M = 0. | |
| 31 for i in range(len(s)-1): | |
| 32 #M += m[i]<<(i*8) | |
| 33 M += float(m[i])/2**((i+1)*8) | |
| 34 # XXX how do we deal negative numbers? | |
| 35 #if m[0] & 0x80: | |
| 36 # M = M - 2^(len(s)) | |
| 37 return M * 2**(e+1) | |
| 38 | |
| 39 def decode_string(s): | |
| 40 nb = ord(s[0]) | |
| 41 s = s[1:nb+2] | |
| 42 r = "" | |
| 43 # XXX why do we need to do this? It's not described in the manual... | |
| 44 for c in s: | |
| 45 r += chr(ord(c) & 0x7F) | |
| 46 return r | |
| 47 | |
| 48 | |
| 49 ### | |
| 50 # Some useful functions | |
| 51 def format_header(header, head_struct, columns=80): | |
| 52 """ | |
| 53 Pretty print a data block (trace, state or coord) | |
| 54 """ | |
| 55 todisp = [] | |
| 56 for row in head_struct: | |
| 57 key = row[0] | |
| 58 val = header.get(key, "N/A") | |
| 59 if isinstance(val, basestring): | |
| 60 val = repr(val) | |
| 61 else: | |
| 62 val = str(val) | |
| 63 todisp.append((key+":", val)) | |
| 64 maxk = max([len(k) for k, v in todisp]) | |
| 65 maxv = max([len(v) for k, v in todisp]) | |
| 66 fmt = "%%-%ds %%-%ds"%(maxk, maxv) | |
| 67 w = maxk+maxv+4 | |
| 68 ncols = columns/w | |
| 69 nrows = len(todisp)/ncols | |
| 70 res = "" | |
| 71 for i in range(nrows): | |
| 72 res += "| ".join([fmt%todisp[j*nrows+i] for j in range(ncols)]) + "\n" | |
| 73 return res | |
| 74 | |
| 75 def decode_header(data, header_struct): | |
| 76 d = data | |
| 77 typ = d[:2] | |
| 78 assert typ == "#A" | |
| 79 | |
| 80 totlen = struct.unpack('>h', d[2:4])[0] | |
| 81 idx = 4 | |
| 82 tt=0 | |
| 83 header = {} | |
| 84 for i, (nam, dtype, fmt, nbytes) in enumerate(header_struct): | |
| 85 if dtype == str: | |
| 86 val = decode_string(d[idx:]) | |
| 87 else: | |
| 88 if fmt: | |
| 89 v = struct.unpack('>'+fmt, d[idx: idx+nbytes])[0] | |
| 90 if isinstance(dtype, dict): | |
| 91 val = dtype.get(int(v), "N/A") | |
| 92 else: | |
| 93 val = dtype(v) | |
| 94 else: | |
| 95 val = dtype(d[idx: idx+nbytes]) | |
| 96 header[nam] = val | |
| 97 idx += nbytes | |
| 98 return header, idx | |
| 17 | 99 |
| 18 ##################### | 100 ##################### |
| 19 # HP3562A constants | 101 # HP3562A constants |
| 20 | 102 |
| 21 # GPIB buffer size is 3x80 characters lines | 103 # GPIB buffer size is 3x80 characters lines |
| 100 (0x10, "MSSM", "Missed sample"), | 182 (0x10, "MSSM", "Missed sample"), |
| 101 (0x20, "TMPR", "Timed preview"), | 183 (0x20, "TMPR", "Timed preview"), |
| 102 (0x40, "ACDA", "Accept date"), | 184 (0x40, "ACDA", "Accept date"), |
| 103 #... | 185 #... |
| 104 ] | 186 ] |
| 187 | |
| 188 |
