; -----------------------

; Title: Random Number Generator.

; Author: Measter

; Date: 2013/12/05

; -----------------------

; Revisions

; 1 - Initial release.

; 2 - Only include dword_mul instead of entire maths library.

; 3 - Added macros.

; 4 - rand_range macro no longer uses the A register.

.include <maths/dword_mul.asm>

.macro set_seed(seed)

set [rand_seed], seed

.endmacro

.macro rand(dest)

jsr rand_func

set dest, [rand_seed]

.endmacro

.macro rand_range(min, max, dest)

sub sp, 1

set [sp], max

sub [sp], min

rand(dest)

mod dest, [sp]

add dest, min

add sp, 1

.endmacro

; Seed for the generator.

:rand_seed

dat 0x1

; Generates a 16-bit random number.

; Input

; [rand_seed] : Seed.

; Output

; [rand_seed] : Result.

:rand_func

set push, a

set push, b

dword_mul(0x015A, 0x4E35, 0x0000, [rand_seed], a, b)

add b, 1

ife ex, 0x1

add a, 1

and a, 0x7FFF

set [rand_seed], a

set b, pop

set a, pop

set pc, pop