[J-core] Pondering j-core kickstarter ideas.

D. Jeff Dionne Jeff at SE-Instruments.com
Thu Oct 19 18:22:32 EDT 2017

J-Core already supports the primitives needed for DSP in fixed point math, it's used extensively in SEI's products built on SMP J-Core SoC designs.   An example is a (real time) GPS receiver, where all the digital filters, DLL/PLL, etc are in fixed point.   The MAC unit provides support for saturation, etc in hardware.  The rest of the GNSS calculations are done in soft floating point on the J2.

Actually, all of SEIs use cases have a single processing component to them... used in real production systems built on J2 or SMP J2.

The SMP J2, or even a single J2 will handily beat the consoles the original SH2 was in http://segaretro.org/Sega_Saturn  The addition of an S-Core DSP or two, the release of which is a ToDo item, will let you do all the things below easily, and has things like fixed point vector rotation in hardware.

> On Oct 20, 2017, at 06:24, Ken Phillis Jr <kphillisjr at gmail.com> wrote:
> I stated this before, but the J2 Core is capable of handling 3D Math.
> The trick is to use Fixed Point Arithmetic[1] to perform calculations.

Have a look at the MAC unit in the J2.   It was designed for this sort of thing.

> Step 1: Add Hardware Acceleration for Fixed Point Calculations
> Step 2: Implement Hardware Vector Math.
> Step 3: Implement a 3D Software Renderer for the Hardware


> [1] Wikipedia: Fixed Point Arithmetic:
> https://en.wikipedia.org/wiki/Fixed-point_arithmetic
> [2] Wikipedia: Playstation 1 Console:
> https://en.wikipedia.org/wiki/PlayStation_(console)
> [3] Wikipedia: Sega Saturn Console: https://en.wikipedia.org/wiki/Sega_Saturn
> [4] Wikipedia: Nintendo GameBoy Advance:
> https://en.wikipedia.org/wiki/Game_Boy_Advance
> [5] Wikipedia: Nintendo DS: https://en.wikipedia.org/wiki/Nintendo_DS
> [6] Github: Libfixmath: https://github.com/PetteriAimonen/libfixmath
> [7] Github: LibfixMatrix: https://github.com/PetteriAimonen/libfixmatrix
> [8] Github: Vector_lib: https://github.com/rampantpixels/vector_lib
> Note: This library uses Floating Point, so The math needs slight changes.
> [9] Github: Tinyrenderer: https://github.com/ssloy/tinyrenderer
> Note: This tutorial is written against mostly Floating Point Math, but
> it can be used with changes to make use of the Fixed point math.
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