One way to measure the accuracy of calculations is with the calculator forensic found here.
I was able to speed the shifting up even more by using another lookup table that let me right shift 4 digits at a time. Instead, a lookup table is used with adds and shifts, which are much faster. This is a very efficient way to compute these functions for processors that cannot multiply or divide quickly. Before processing void puts ( unsigned char *msg)The trig and log functions are computed using CORDIC routines. These are usually ignored by the compiler if they are not recognized, so they are a convenient way to communicate with the preprocessor. To mark variables as external, #pragma directives are used. External variables are all stored as pointers, so the PC version will work exactly the same with or without the preprocessor. A simple equation like: X+=Y*Z-Q would become something like this (assuming we are passing pointers): RAM_Write(X,RAM_Read(X)+(RAM_Read(Y)*RAM_Read(Z)-RAM_Read(Q)) To simplify things, I wrote a preprocessor program that looks for any variables that need to be stored in external RAM and converts access to them to function calls. I wanted to access this memory using variables but there is no convenient way to do this since every variable requires a function to access it.
On Windows:gcc -o rpncalc.exe rpnmain_pc.cOn Linux:gcc -lncurses -o rpncalc rpnmain_pc.cNumbers are stored in unpacked BCD format on an external SRAM chip. You can download it from GitHub if you want to test out the functionality: rpnmain_pc.c It will compile for Windows if #WINDOWS is defined or for Linux with the ncurses library if #LINUX is defined. While I was writing the code for BCD calculations, I used a console program to test the routines. The interface shows 4 levels of the stack, similar to some HP calculators. Functions: (a)sin, (a)cos, (a)tan, y^x, x root y, e^x, ln, 10^x, log, mod.Internal accuracy configurable from 6 to 32 decimal places.
This is a scientific calculator I built that uses RPN notation.
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