cpct_getRandom_mxor_u32

Gets a 32-bit pseudo-random number using Marsaglia’s XOR-shift algorithm (using a 32-bits state)

C Definition

u32 cpct_getRandom_mxor_u32 ();

Assembly call

call cpct_getRandom_mxor_u32_asm

Return value (Assembly calls, return DE:HL=random 16-bits)

Known limitations

• This function will never produce a 0 as random 32-bits integer value.  If you require a 0 to be produced, use returned value minus 1.
• This function does not repeat a single 32-bits value in the sequence it produces until it finishes its period ((2^32)-1).  Use other functions if you require random numbers to sometimes repeat values (which is often desirable)

Details

This function uses cpct_nextRandom_mxor_u32 to produce a sequence of 32-bits pseudo-random numbers.  It uses cpct_mxor32_seed to store the last returned random 32-bits value: this is required to produce the next value in the sequence.

To know more about how these 32-bits numbers are produced, check cpct_nextRandom_mxor_u32 documentation.

Destroyed Register values

AF, BC, DE, HL

Required memory

57 bytes divided in,

• 18 bytes (this function’s code)
• +35 bytes (from cpct_nextRandom_mxor_u32 function’s code)
• +4 bytes (from cpct_mxor32_seed)

Time Measures

   Case     | microSecs (us) | CPU Cycles
-----------------------------------------
    Any     |      67        |    268
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