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Wednesday, July 16, 2014

Atlast 2.0 (64-bit) Released

I have just posted the first update to Atlast since 2007. Atlast is a FORTH-like language toolkit intended to make it easy to open the internal facilities of applications to users, especially on embedded platforms with limited computing and memory resources.

Like FORTH, Atlast provides low-level access to the memory architecture of the machine on which it runs, and is sensitive to the length of data objects. The 1.x releases of Atlast assume integers and pointers are 32 bit quantities and floating point numbers are 64 bit, occupying two stack items. This assumption is no longer the case when building programs in native mode on 64-bit systems: integers, pointers, and floating point values are all 64 bits.

Release 2.0 of Atlast is a dedicated 64-bit implementation of the language. If you are developing on a 64-bit platform and are confident you will only target such platforms, it provides a simpler architecture (no need for double word operations for floating point) and a larger address space and integers. This comes at the cost of loss of source code compatibility with the 32-bit 1.x releases, particularly for floating point code. If your target platform is a 32-bit system and your development machine is 64-bit, it's best to use version 1.2 (which is functionally identical to 2.0), cross-compiled as 32-bit code. If you don't use floating point or do low-level memory twiddling, it's likely your programs will work on both 32- and 64-bit versions.

Although Atlast includes comprehensive pointer and stack limit checking, it is not memory-safe, and consequently I do not encourage its use in modern applications. When it was originally developed in the late 1980s, its ability to fit in a small memory footprint was of surpassing importance. With the extravagant memory and compute power of contemporary machines, this is less important and other scripting languages which are both entirely safe and less obscure in syntax will usually be preferable. Still, some people working with embedded systems very close to the hardware continue to find Atlast useful, and this release updates it for 64-bit architectures.

The distribution archive has been re-organised in 2.0, collecting the regression test, examples from the user manual, and benchmarks in subdirectories. An implementation of my floating point benchmark is included among the examples.

Posted at July 16, 2014 23:56