SCBNDS (immediate)

Set Bounds (immediate) derives Capability Bounds using the source Capability register and a length from an immediate offset and writes the result to the destination Capability register. If the source capability is sealed, the Capability Tag written to the destination Capability register is cleared

It has encodings from 2 classes: Scaled and Unscaled

Scaled

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
1	1	0	0	0	0	1	0	1	1	0	imm6						1	1	1	1	0	Cn					Cd
																	S

SCBNDS <Cd|CSP>, <Cn|CSP>, #<imm>, LSL #4

integer n = UInt(Cn); integer d = UInt(Cd); bits(65) length = if S == '1' then ZeroExtend(imm6:'0000',65) else ZeroExtend(imm6,65);

Unscaled

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
1	1	0	0	0	0	1	0	1	1	0	imm6						0	1	1	1	0	Cn					Cd
																	S

SCBNDS <Cd|CSP>, <Cn|CSP>, #<imm>

integer n = UInt(Cn); integer d = UInt(Cd); bits(65) length = if S == '1' then ZeroExtend(imm6:'0000',65) else ZeroExtend(imm6,65);

Assembler Symbols

<Cd|CSP>

Is the capability name of the destination register or stack pointer, encoded in the "Cd" field.

<Cn|CSP>

Is the capability name of the source register or stack pointer, encoded in the "Cn" field.

<imm>

Is the unsigned immediate operand, in the range 0 to 63, encoded in the "imm6" field.

Operation

CheckCapabilitiesEnabled(); Capability operand = if n == 31 then CSP[] else C[n]; Capability result = CapSetBounds(operand, length, TRUE); if CapIsSealed(operand) then result = CapWithTagClear(result); if d == 31 then CSP[] = result; else C[d] = result;

Internal version only: isa v32.13, AdvSIMD v29.04, pseudocode morello-2022-01_rc2, capabilities morello-2022-01_rc2 ; Build timestamp: 2022-01-11T11:23