I’ve thought about this some more.
Suppose your task is to write audio DSP in assembly. Then what is a good tool for this?
One possibility is to use a processor specifically designed for DSP. There are many, but here’s one that’s quite easy to use. The Spin Semiconductor FV-1. The FV-1 has integrated stereo ADC and DAC, and control inputs, so it is pretty much complete audio DSP system on a chip.
There is only 28 assembly language instructions for it, but many of them are advanced DSP sorts of instructions, that do various multiply and accumulate operations in hardware in just one assembly language instruction. See :
The FV-1 Instrruction set.
You can accomplish very advanced DSP operations like reverb, pitch-shifting, distortion and other effects with short, like under 50 assembly language instructions. Here is a whole list of example programs to start from :
Spin Semiconductor - Free DSP Programs
You can buy a complete ready to go developer board for this so you are pretty much ready to go.
This product has been used in a variety of guitar pedals, and is also used in the Les diffYUseurs effects emulator developed by Yves Usson. ( thread )
ADDED : The Spin Semiconductor FV-1 is also used in the Tiptop Audio Z-DSP Eurorack module ( still available new ), and you get to write SpinASM programs for that.