tracelib

This provides an implementation of a simulation trace file writer interface. Rather than providing support for a set of formats, the interface instead assumes the existennce of a shared library that can be loaded in at run-time that provides the appropriate file-format-specific functions for creating a trace file.

Sample implementations for generating ACT trace files, VCD files, and LXT2 files are provided. A blank template file (template.c) is provided that summarizes the functions that must be provided. Header file tracelib.h provides details of the interface.

Building

There are two ways to build the library.

• As an ACT support library: follow the instructions for building any ACT tool.
• As a standalone library without any dependencies on ACT: use cmake to build and install the library (mkdir build; cd build; cmake -DCMAKE_INSTALL_PREFIX=<install-dir> ..; make && make install)

Usage

To begin using the interface, a shared object library must be loaded.

• act_extern_trace_func_t *act_trace_load_format (char *prefix, const char *dl)
  • The prefix string is normally the name of the format. Functions in the shared object library that implement the necessary API start with <prefix>_.
  • dl is the path to the shared object library. If omitted, the default name is used, which is libtrace_<prefix>.so. If the library was built as an ACT support library, the $ACT_HOME/lib/ directory is checked for the library as well.
  • If successful, a pointer to the trace file API is returned that is used to create a trace file.

A shared object library must provide a complete set of functions for either a reader or a writer (ideally both). The file template.c has a dummy template with blank functions that are named correctly. A trace file format library has to provide implementations of those API functions.

Writer API

• act_trace_t *act_trace_create (act_extern_trace_func_t *, const char *name, float stop_time, float ts, int mode)

  • This creates the trace file with the specified name. It takes the trace file API as an argument, as well as the end time for the simulation trace and the time resolution.
  • The mode argument can be zero or one; zero means that the trace file created uses the API where the time is specified as a floating-point number. If mode is one, the time is specified as an unsigned integer, where the time in SI units is obtained by multiplying the integer by ts. Note that a trace file API can support both interfaces, but a specific trace file can only use one of the two options.

• void *act_trace_add_signal (act_trace_t *, act_signal_type_t type, const char *s, int width)

  • This returns a signal handle that to be used when recording signal changes. It returns NULL on failure.
  • nm is the name of the signal, type (one of ACT_SIG_BOOL, ACT_SIG_INT, ACT_SIG_CHAN, ACT_SIG_ANALOG) specifies the signal type, and for channel and integer arguments the width is the bit-width of the data.

• int act_trace_init_start (act_trace_t *) and int act_trace_init_end (act_trace_t *)

  • This indicates the start of the block of initial values for signals. Signal initial values are recorded with time set to zero and the signal change API (below).
  • The functions return 1 on success, 0 on failure.

• Signal changes for mode zero are recorded with the following API calls

  • int act_trace_analog_change (act_trace_t *, void *node, float t, float v)
  • int act_trace_digital_change (act_trace_t *, void *node, float t, unsigned long v)
  • int act_trace_wide_digital_change (act_trace_t *, void *node, float t, int len, unsigned long *v)
    • This call is used to support wider than 64-bit values recorded in the trace. len (more than one) is the size of the v array, where the least significant 64-bit chunk is in v[0].
  • int act_trace_chan_change (act_trace_t *, void *node, float t, act_chan_state_t s, unsigned long v)
  • int act_trace_wide_chan_change (act_trace_t *, void *node, float t, act_chan_state_t s, unsigned long v)
    • These calls are similar to the digital change calls, except they also include a channel state parameter s. The state can be ACT_CHAN_IDLE, ACT_CHAN_SEND_BLOCKED, ACT_CHAN_RECV_BLOCKED, or ACT_CHAN_VALUE. The v field is only used when a ACT_CHAN_VALUE is specified.
  • All functions return 1 on success, 0 on failure. The node pointer is the handle returned when the signal was added.

• Signal changes for mode one are recoded with a similar API, except that the time is specified as an array of unsigned long values (similar to the wide integer/channel).

  • int act_trace_analog_change_alt (act_trace_t *, void *node, int len, unsigned long *tm, float v)
  • int act_trace_digital_change_alt (act_trace_t *, void *node, int len, unsigned long *tm, unsigned long v)
  • int act_trace_wide_digital_change_alt (act_trace_t *, void *node, int len, unsigned long *tm, int lenv, unsigned long *v)
  • int act_trace_chan_change_alt (act_trace_t *, void *node, int len, unsigned long *tm, act_chan_state_t s, unsigned long v)
  • int act_trace_wide_chan_change_alt (act_trace_t *, void *node, int len, unsigned long *tm, act_chan_state_t s, int lenv, unsigned long *v)
  • All functions return 1 on success, 0 on failure.

• int act_trace_close (act_trace_t *)

  • Closes the trace file and releases storage.

Finally, the API enforces a simple state machine in terms of the order in which these functions are to be called. The order must be:

1. Create trace file
2. Add signals
3. Start initial block
4. Add initial values
5. End initial block
6. Any signal changes for the rest of the simulation
7. Close trace file

Reader API

• act_trace_t *act_trace_open (act_extern_trace_func_t *, const char *name, int mode)

  • This opens a trace file with the specified name for reading. It takes the trace file API as an argument.
  • The mode argument can be zero or one; zero means that the trace file created uses the API where the time is specified as a floating-point number. If mode is one, the time is specified as an unsigned integer, where the time in SI units.

• void act_trace_header (act_trace_t *, float *stop_time, float *dt)

  • Read the trace file header and return the stop time as well as the timestep resolution. If the header doesn't contain a parameter, -1 is returned.

• void *act_trace_lookup (act_trace_t *, const char *name)

  • This returns a signal handle that to be used to access the signal value. It returns NULL on failure (e.g. name does not exist in the trace file).
  • name is the name of the signal name.

• act_signal_type_t act_trace_sigtype (act_trace_t *, void *sig)

  • This returns the signal type given the signal pointer.

• act_signal_val_t act_trace_get_signal (act_trace_t *, void *sig)

  • This returns the current value of the specified signal

• Time is advanced when reading a trace file with two different APIs. For mode zero, the following API is used

  • void act_trace_advance_steps (act_trace_t *, int steps)

• Time is advanced when reading a trace file with two different APIs. For mode one, the following API is used

  • void act_trace_advance_steps (act_trace_t *, float dt)

• You can determine if there is more data in the trace file using the following API

  • int act_trace_has_more_data (act_trace_t *)

• int act_trace_close (act_trace_t *)

  • Closes the trace file and releases storage.