Subtract (extended register) subtracts a sign or zero-extended register value, followed by an optional left shift amount, from a register value, and writes the result to the destination register. The argument that is extended from the <Rm> register can be a byte, halfword, word, or doubleword.
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 | 0 | 0 | 1 | Rm | option | imm3 | 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; ExtendType extend_type = DecodeRegExtend(option); integer shift = UInt(imm3); if shift > 4 then ReservedValue();
<Wd|WSP> |
Is the 32-bit name of the destination general-purpose register or stack pointer, encoded in the "Rd" field. |
<Wn|WSP> |
Is the 32-bit name of the first source general-purpose register or stack pointer, encoded in the "Rn" field. |
<Wm> |
Is the 32-bit name of the second general-purpose source register, encoded in the "Rm" field. |
<Xd|SP> |
Is the 64-bit name of the destination general-purpose register or stack pointer, encoded in the "Rd" field. |
<Xn|SP> |
Is the 64-bit name of the first source general-purpose register or stack pointer, encoded in the "Rn" field. |
<R> |
Is a width specifier,
encoded in
option:
|
<m> |
Is the number [0-30] of the second general-purpose source register or the name ZR (31), encoded in the "Rm" field. |
<extend> |
For the 32-bit variant: is the extension to be applied to the second source operand,
encoded in
option:
| ||||||||||||||||||
For the 64-bit variant: is the extension to be applied to the second source operand,
encoded in
option:
|
bits(datasize) result; bits(datasize) operand1 = if n == 31 then SP[] else X[n]; bits(datasize) operand2 = ExtendReg(m, extend_type, shift); operand2 = NOT(operand2); (result, -) = AddWithCarry(operand1, operand2, '1'); if d == 31 then SP[] = result; else X[d] = result;
Internal version only: isa v25.07, AdvSIMD v23.0, pseudocode v31.3
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