From 3994fee595605c5981d023c29b5d9d8e170d9adc Mon Sep 17 00:00:00 2001

From: LRFLEW <LRFLEW@aol.com>

Date: Mon, 7 Oct 2019 22:37:34 -0500

Subject: [PATCH 057/170] Significantly faster rand() implementation

---

 libsrc/common/rand.s | 22 ++++++----------------

 1 file changed, 6 insertions(+), 16 deletions(-)

diff --git a/libsrc/common/rand.s b/libsrc/common/rand.s

index 102dd5be..fc23b6ee 100644

--- a/libsrc/common/rand.s

+++ b/libsrc/common/rand.s

@@ -35,27 +35,17 @@ rand:   .dword   1

 .code

 _rand:  clc

-        lda     rand+0          ; SEED *= $01010101

-        adc     rand+1

-        sta     rand+1

-        adc     rand+2

-        sta     rand+2

-        adc     rand+3

-        sta     rand+3

-        clc

-        lda     rand+0          ; SEED += $31415927

-        adc     #$27

+        lda     rand+0          ; SEED += $B3

+        adc     #$B3

         sta     rand+0

-        lda     rand+1

-        adc     #$59

+        adc     rand+1          ; SEED *= $01010101

         sta     rand+1

-        lda     rand+2

-        adc     #$41

+        adc     rand+2

         sta     rand+2

         and     #$7f            ; Suppress sign bit (make it positive)

         tax

-        lda     rand+3

-        adc     #$31

+        lda     rand+2

+        adc     rand+3

         sta     rand+3

         rts                     ; return bit (16-22,24-31) in (X,A)

-- 

2.26.0