implement prefix calculator

calculator/README.md

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+# Calculator
+
+This program accepts an arithmetic expression in prefix notation
+on standard input and prints the result on standard output.
+
+Supported operations:
+
+- Addition
+- Subtraction
+- Multiplication
+- Division
+
+All calculations are preformed on Integers in range $[-2^{23}, 2^{23} - 1]$. Negative numbers can be written as `(- 0 n)`, where `n` is the number
+
+Here are some examples:
+
+```{bash}
+(* 21 2)
+00000042
+(/ 6 (* 2 (+ 2 1)))
+00000001
+(* (/ 6 2) (+ 2 1))
+00000009
+(- 33 (* 4 25))
+-00000067
+
+```
+
+- Source code: calc.asm
+- Frequency: any (faster is faster)
+- Author: Jakob Jesenko, 2026