RNDR, Random Number
The RNDR characteristics are:
Purpose
Random Number. Returns a 64-bit random number which is reseeded from the True Random Number source at an IMPLEMENTATION DEFINED rate.
If the hardware returns a genuine random number, PSTATE.NZCV is set to 0b0000.
If the instruction cannot return a genuine random number in a reasonable period of time, PSTATE.NZCV is set to 0b0100 and the data value returned is 0.
RNDR is a read-only register.
Configuration
This register is present only when FEAT_RNG is implemented. Otherwise, direct accesses to RNDR are UNDEFINED.
Attributes
RNDR is a 64-bit register.
Field descriptions
The RNDR bit assignments are:
| 63 | 62 | 61 | 60 | 59 | 58 | 57 | 56 | 55 | 54 | 53 | 52 | 51 | 50 | 49 | 48 | 47 | 46 | 45 | 44 | 43 | 42 | 41 | 40 | 39 | 38 | 37 | 36 | 35 | 34 | 33 | 32 |
| RNDR | |||||||||||||||||||||||||||||||
| RNDR | |||||||||||||||||||||||||||||||
| 31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
RNDR, bits [63:0]
Random Number. Returns a 64-bit Random Number which is reseeded from the True Random Number source at an IMPLEMENTATION DEFINED rate.
On a Warm reset, this field resets to an architecturally UNKNOWN value.
Accessing the RNDR
Accesses to this register use the following encodings:
MRS <Xt>, RNDR
| op0 | op1 | CRn | CRm | op2 |
|---|---|---|---|---|
| 0b11 | 0b011 | 0b0010 | 0b0100 | 0b000 |
if PSTATE.EL == EL0 then
return RNDR;
elsif PSTATE.EL == EL1 then
return RNDR;
elsif PSTATE.EL == EL2 then
return RNDR;
elsif PSTATE.EL == EL3 then
return RNDR;