more sane directory name, updated binaries

src/basic/math/e0be.rnd_generate.s

@@ -0,0 +1,77 @@
+// #LAYOUT# STD *       #TAKE
+// #LAYOUT# *   BASIC_0 #TAKE
+// #LAYOUT# *   *       #IGNORE
+
+//
+// A fast pseudorandom generator, modified idea from:
+// - https://codebase64.org/doku.php?id=base:32bit_galois_lfsr
+//
+// Output:
+// - FAC1
+//
+// See also:
+// - https://www.atarimagazines.com/compute/issue72/random_numbers.php
+//
+
+rnd_generate:
+
+	asl RNDX+1
+	rol RNDX+2
+	rol RNDX+3
+	rol RNDX+4
+
+	bcs rnd_generate_copy
+
+	lda RNDX+1
+	eor #$B7
+	sta RNDX+1
+
+	lda RNDX+2
+	eor #$1D
+	sta RNDX+2
+
+	lda RNDX+3
+	eor #$C1
+	sta RNDX+3
+
+	lda RNDX+4
+	eor #$04
+	sta RNDX+4
+
+	sec                                // make sure Carry is always set, for adc
+
+	// FALLTROUGH
+
+rnd_generate_copy:
+
+	// Copy the generated number to FAC1, mangle it a little
+
+	lda RNDX+3
+	adc #$C6
+	sta FAC1_mantissa+0
+
+	lda RNDX+1
+	eor #$4E
+	sta FAC1_mantissa+1
+
+	lda RNDX+4
+	eor #$62
+	sta FAC1_mantissa+2
+
+	lda RNDX+2
+	bit RNDX+2
+	rol
+	sta FAC1_mantissa+3
+
+	// FALLTROUGH
+
+rnd_generate_finalize:
+
+	lda #$00
+	sta FAC1_sign
+	
+	lda #$80
+	sta FACOV                          // just to prevent 0 after normalization
+	sta FAC1_exponent
+	
+	jmp normal_FAC1