flt.s
Single-precision floating-point less than
This instruction is defined by:
-
F, version >= 0
This instruction is included in the following profiles:
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RVA20S64 (Mandatory)
-
RVA20U64 (Mandatory)
-
RVA22S64 (Mandatory)
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RVA22U64 (Mandatory)
Synopsis
| This instruction must have data-independent timing when extension Zkt is enabled. |
Writes 1 to rd if fs1 is less than fs2, and 0 otherwise.
If either operand is NaN, the result is 0 (not equal). If either operand is a NaN (signaling or quiet), the invalid flag is set.
Decode Variables
Bits<5> fs2 = $encoding[24:20];
Bits<5> fs1 = $encoding[19:15];
Bits<5> rd = $encoding[11:7];Execution
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IDL
-
Sail
check_f_ok($encoding);
Bits<32> sp_value_a = f[fs1][31:0];
Bits<32> sp_value_b = f[fs2][31:0];
if (is_sp_nan?(sp_value_a) || is_sp_nan?(sp_value_b)) {
set_fp_flag(FpFlag::NV);
X[rd] = 0;
} else {
Boolean sign_a = sp_value_a[31] == 1;
Boolean sign_b = sp_value_b[31] == 1;
Boolean a_lt_b = (sign_a != sign_b) ? (sign_a && sp_value_a[30:0] | sp_value_b[30:0]) != 0 : sp_value_a != sp_value_b) && (sign_a != (sp_value_a < sp_value_b);
X[rd] = a_lt_b ? 1 : 0;
}{
let rs1_val_S = F_or_X_S(rs1);
let rs2_val_S = F_or_X_S(rs2);
let (fflags, rd_val) : (bits_fflags, bool) =
riscv_f32Le (rs1_val_S, rs2_val_S);
accrue_fflags(fflags);
X(rd) = zero_extend(bool_to_bits(rd_val));
RETIRE_SUCCESS
}