Bidirectional debugger

I wrote a few articles on debugging for International Developer magazine & en-route ran across a reversable debugger for Linux called UndoDB.

This straps onto dgb or ddd or whatever, and adds reversability. Where you once stepped the cursor over instructions, now you can step it under those instructions, back-stepping or completely time-jumping your program backwards. Smoothly.

Needless to say, this can make debugging much easier, since you can now start with an exposed problem, and back-track until the problem goes away. The rewinding even includes putting back the pseudo-random values initially placed in local variables (in C), so a bug which depends on one of these values can be re-created. This made choosing examples for my articles very easy.

I was also pleased to see free “not-for-profit” licences available, and a 30-day trial run, so one can test it out for one’s self, to see how well it really does work before buying it. Very reassuring.

Comments

every-application-is-part-of-a-toolkit at work

I have a LibreOffice Impress slideshow that I wish to turn into a narrated video. 1. export the slideshow as PNG images (if that is partially broken — as at now — at higher resolutions, Export Directly as PDF then use ‘pdftoppm’ (from the poppler-utils package) to do the same). 2. write a small C program (63 lines including comments) to display those images one at a time, writing a config file entry for Imagination (default transition: ‘cross fade’) based on when the image-viewer application (‘display,’ from the GraphicsMagick suite) is closed on each one; run that, read each image aloud, then close each image in turn. 3. run ‘Imagination’ over the config file to produce a silent MP4 video with the correct timings. 4. run ‘Audacity’ to record speech while using ‘SMPlayer’ to display the silent video, then export that recording as a WAV file. 4a. optionally, use ‘TiMIDIty’ to convert a non-copyright-encumbered MIDI tune to WAV, then import that and blend it with the speech (as a quiet b

new life for an old (FTX) PSU, improved life for one human

the LEDs on this 5m strip happen to emit light centred on a red that does unexpectedly helpful things to (and surprisingly deeply within) a human routinely exposed to it. it has been soldered to a Molex connector, plugged into a TFX power supply from a (retired: the MoBo is cactus) Small Form Factor PC, the assorted PSU connectors (and loose end from the strip) have been taped over. the LED strip cost $10.24 including postage, the rest cost $0, the PSU is running at 12½% of capacity, consumes less power than a laptop plug-pack despite running a fan. trial runs begin today.

boundaries

pushing the actual boundaries of the physical (not extremes, the boundaries themselves) can often remove barriers not otherwise perceived. one can then often resolve an issue itself, rather than merely stonewalling at the physical consequences of the issue.

Plantagenet Penguinista

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