Table vector Lookup. This instruction reads each value from the vector elements in the index source SIMD&FP register, uses each result as an index to perform a lookup in a table of bytes that is described by one to four source table SIMD&FP registers, places the lookup result in a vector, and writes the vector to the destination SIMD&FP register. If an index is out of range for the table, the result for that lookup is 0. If more than one source register is used to describe the table, the first source register describes the lowest bytes of the table.
Depending on the settings in the CPACR_EL1, CPTR_EL2, and CPTR_EL3 registers, and the current Security state and Exception level, an attempt to execute the instruction might be trapped.
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 |
0 | Q | 0 | 0 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | Rm | 0 | len | 0 | 0 | 0 | Rn | Rd | |||||||||||||
op |
TBL <Vd>.<Ta>, { <Vn>.16B, <Vn+1>.16B, <Vn+2>.16B, <Vn+3>.16B }, <Vm>.<Ta>
integer d = UInt(Rd); integer n = UInt(Rn); integer m = UInt(Rm); integer datasize = if Q == '1' then 128 else 64; integer elements = datasize DIV 8; integer regs = UInt(len) + 1; boolean is_tbl = (op == '0');
<Vd> |
Is the name of the SIMD&FP destination register, encoded in the "Rd" field. |
<Ta> |
Is an arrangement specifier,
encoded in
|
<Vn+1> |
Is the name of the second SIMD&FP table register, encoded as "Rn" plus 1 modulo 32. |
<Vn+2> |
Is the name of the third SIMD&FP table register, encoded as "Rn" plus 2 modulo 32. |
<Vn+3> |
Is the name of the fourth SIMD&FP table register, encoded as "Rn" plus 3 modulo 32. |
<Vm> |
Is the name of the SIMD&FP index register, encoded in the "Rm" field. |
CheckFPAdvSIMDEnabled64(); bits(datasize) indices = V[m]; bits(128*regs) table = Zeros(); bits(datasize) result; integer index; // Create table from registers for i = 0 to regs - 1 table<128*i+127:128*i> = V[n]; n = (n + 1) MOD 32; result = if is_tbl then Zeros() else V[d]; for i = 0 to elements - 1 index = UInt(Elem[indices, i, 8]); if index < 16 * regs then Elem[result, i, 8] = Elem[table, index, 8]; V[d] = result;
If PSTATE.DIT is 1:
Internal version only: isa v33.11seprel, AdvSIMD v29.05, pseudocode v2021-09_rel, sve v2021-09_rc3d ; Build timestamp: 2021-10-06T11:41
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