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Feature #508

Updated by Mathieu Desnoyers about 8 years ago


 The attached patch modifies the hello.cxx test (from lttng-ust 2.1.1) to add an array of floats argument. 
 as you see in the following output (babeltrace v1.0.3 with the python bindings patchs), the field floatarrfield shows ints instead of the expected floats: 

 <pre> 
 $ rm -rf ~/lttng-traces/ ; lttng create && lttng enable-event -a -u && lttng start && ./run && lttng stop && lttng destroy && babeltrace ~/lttng-traces | head -n 2 
 Session auto-20130419-222314 created. 
 Traces will be written in /home/sbarthelemy/lttng-traces/auto-20130419-222314 
 All UST events are enabled in channel channel0 
 Tracing started for session auto-20130419-222314 
 Hello, World! 
 Tracing...    done. 
 Waiting for data availability 
 Tracing stopped for session auto-20130419-222314 
 Session auto-20130419-222314 destroyed 
 [22:23:14.605465399] (+?.?????????) ald-0987-de:hello:30232 ust_tests_hello:tptest: { cpu_id = 5 }, { intfield = 0, intfield2 = 0x0, longfield = 0, netintfield = 0, netintfieldhex = 0x0, arrfield1 = [ [0] = 1, [1] = 2, [2] = 3 ], arrfield2 = "test", _seqfield1_length = 4, seqfield1 = [ [0] = 116, [1] = 101, [2] = 115, [3] = 116 ], _seqfield2_length = 4, seqfield2 = "test", stringfield = "test", floatfield = 2222.1, doublefield = 2.1, floatarrfield = [ [0] = 1066192077, [1] = 1074580685, [2] = 1079194419 ] } 
 [22:23:14.605470207] (+0.000004808) ald-0987-de:hello:30232 ust_tests_hello:tptest: { cpu_id = 5 }, { intfield = 1, intfield2 = 0x1, longfield = 1, netintfield = 1, netintfieldhex = 0x1, arrfield1 = [ [0] = 1, [1] = 2, [2] = 3 ], arrfield2 = "test", _seqfield1_length = 4, seqfield1 = [ [0] = 116, [1] = 101, [2] = 115, [3] = 116 ], _seqfield2_length = 4, seqfield2 = "test", stringfield = "test", floatfield = 2222.1, doublefield = 2.1, floatarrfield = [ [0] = 1066192077, [1] = 1074580685, [2] = 1079194419 ] } 
 </pre> 

 as a workaround, the floating point value can be retrieved in python using: 
 <pre> 
 In [1]: import struct 

 In [2]: struct.unpack('f', struct.pack('i', 1066192077)) 
 Out[2]: (1.100000023841858,) 
 </pre>

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