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Subtract (shifted register) subtracts an optionally-shifted register value from a register value, and writes the result to the destination register.
Subtract (shifted register) subtracts an optionally-shifted register value from a register value, and writes the result to the destination register.
This instruction is used by the alias NEG (shifted register).
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 |
sf | 1 | 0 | 0 | 1 | 0 | 1 | 1 | shift | 0 | Rm | imm6 | Rn | Rd | ||||||||||||||||||
op | S |
integer d = UInt(Rd); integer n = UInt(Rn); integer m = UInt(Rm); integer datasize = if sf == '1' then 64 else 32; boolean sub_op = (op == '1'); boolean setflags = (S == '1'); if shift == '11' then UNDEFINED; if sf == '0' && imm6<5> == '1' then UNDEFINED; ShiftType shift_type = DecodeShift(shift); integer shift_amount = UInt(imm6);
<Wd> | Is the 32-bit name of the general-purpose destination register, encoded in the "Rd" field. |
<Wn> | Is the 32-bit name of the first general-purpose source register, encoded in the "Rn" field. |
<Wm> | Is the 32-bit name of the second general-purpose source register, encoded in the "Rm" field. |
<Xd> | Is the 64-bit name of the general-purpose destination register, encoded in the "Rd" field. |
<Xn> | Is the 64-bit name of the first general-purpose source register, encoded in the "Rn" field. |
<Xm> | Is the 64-bit name of the second general-purpose source register, encoded in the "Rm" field. |
<amount> | For the 32-bit variant: is the shift amount, in the range 0 to 31, defaulting to 0 and encoded in the "imm6" field. |
For the 64-bit variant: is the shift amount, in the range 0 to 63, defaulting to 0 and encoded in the "imm6" field. |
Alias | Is preferred when |
---|---|
NEG (shifted register) | Rn == '11111' |
bits(datasize) result; bits(datasize) operand1 = X[n]; bits(datasize) operand2 = ShiftReg(m, shift_type, shift_amount); bits(4) nzcv; bit carry_in; if sub_op then operand2 = NOT(operand2); carry_in = '1'; else carry_in = '0'; (result, nzcv) = AddWithCarry(operand1, operand2, carry_in); if setflags then PSTATE.<N,Z,C,V> = nzcv; X[d] = result;
If PSTATE.DIT is 1:
Internal version only: isa v32.13v32.12, AdvSIMD v29.05v29.04, pseudocode v2020-12v2020-09_xml, sve v2020-12v2020-09_rc3
; Build timestamp: 2020-12-16T142020-11-18T17:1723
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