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Merge pull request #438 from bbbradsmith/ca65_rand_comment

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rand.s comment update
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Oliver Schmidt 2017-05-26 15:16:42 +02:00 committed by GitHub
commit 035baa49bd
1 changed files with 9 additions and 4 deletions
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libsrc/common/rand.s
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@ -2,6 +2,7 @@
; Randum number generator
;
; Written and donated by Sidney Cadot - sidney@ch.twi.tudelft.nl
; 2016-11-07, modified by Brad Smith
;
; May be distributed with the cc65 runtime using the same license.
;
@ -13,10 +14,14 @@
; Multiplier must be 1 (mod 4)
; Added value must be 1 (mod 2)
; This guarantees max. period (2**32)
; Bits 8-22 are returned (positive 2-byte int)
; where 0 is LSB, 31 is MSB.
; This is better as lower bits exhibit easily
; detectable patterns.
; The lowest bits have poor entropy and
; exhibit easily detectable patterns, so
; only the upper bits 16-22 and 24-31 of the
; 4-byte state are returned.
;
; The best 8 bits, 24-31 are returned in the
; low byte A to provide the best entropy in the
; most commonly used part of the return value.
;
.export _rand, _srand