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/*=======================================================================================*/
/* This Sail RISC-V architecture model, comprising all files and */
/* directories except where otherwise noted is subject the BSD */
/* two-clause license in the LICENSE file. */
/* */
/* SPDX-License-Identifier: BSD-2-Clause */
/*=======================================================================================*/
/* ******************************************************************************* */
/* This file implements part of the vector extension. */
/* Chapter 6: Configuration-Setting Instructions */
/* ******************************************************************************* */
mapping sew_flag : string <-> bits(3) = {
"e8" <-> 0b000,
"e16" <-> 0b001,
"e32" <-> 0b010,
"e64" <-> 0b011
}
mapping maybe_lmul_flag : string <-> bits(3) = {
"" <-> 0b000, /* m1 by default */
sep() ^ "mf8" <-> 0b101,
sep() ^ "mf4" <-> 0b110,
sep() ^ "mf2" <-> 0b111,
sep() ^ "m1" <-> 0b000,
sep() ^ "m2" <-> 0b001,
sep() ^ "m4" <-> 0b010,
sep() ^ "m8" <-> 0b011
}
mapping maybe_ta_flag : string <-> bits(1) = {
"" <-> 0b0, /* tu by default */
sep() ^ "ta" <-> 0b1,
sep() ^ "tu" <-> 0b0
}
mapping maybe_ma_flag : string <-> bits(1) = {
"" <-> 0b0, /* mu by default */
sep() ^ "ma" <-> 0b1,
sep() ^ "mu" <-> 0b0
}
/* ****************************** vsetvli & vsetvl ******************************* */
union clause ast = VSET_TYPE : (vsetop, bits(1), bits(1), bits(3), bits(3), regidx, regidx)
mapping encdec_vsetop : vsetop <-> bits(4) ={
VSETVLI <-> 0b0000,
VSETVL <-> 0b1000
}
mapping clause encdec = VSET_TYPE(op, ma, ta, sew, lmul, rs1, rd) if haveVExt()
<-> encdec_vsetop(op) @ ma @ ta @ sew @ lmul @ rs1 @ 0b111 @ rd @ 0b1010111 if haveVExt()
function clause execute VSET_TYPE(op, ma, ta, sew, lmul, rs1, rd) = {
let VLEN_pow = get_vlen_pow();
let ELEN_pow = get_elen_pow();
let LMUL_pow_ori = get_lmul_pow();
let SEW_pow_ori = get_sew_pow();
let ratio_pow_ori = SEW_pow_ori - LMUL_pow_ori;
/* set vtype */
match op {
VSETVLI => {
vtype.bits = 0b0 @ zeros(sizeof(xlen) - 9) @ ma @ ta @ sew @ lmul
},
VSETVL => {
let rs2 : regidx = sew[1 .. 0] @ lmul;
vtype.bits = X(rs2)
}
};
/* check legal SEW and LMUL and calculate VLMAX */
let LMUL_pow_new = get_lmul_pow();
let SEW_pow_new = get_sew_pow();
if SEW_pow_new > LMUL_pow_new + ELEN_pow then {
/* Note: Implementations can set vill or trap if the vtype setting is not supported.
* TODO: configuration support for both solutions
*/
vtype.bits = 0b1 @ zeros(sizeof(xlen) - 1); /* set vtype.vill */
vl = zeros();
print_reg("CSR vtype <- " ^ BitStr(vtype.bits));
print_reg("CSR vl <- " ^ BitStr(vl));
return RETIRE_SUCCESS
};
let VLMAX = int_power(2, VLEN_pow + LMUL_pow_new - SEW_pow_new);
/* set vl according to VLMAX and AVL */
if (rs1 != 0b00000) then { /* normal stripmining */
let rs1_val = X(rs1);
let AVL = unsigned(rs1_val);
vl = if AVL <= VLMAX then to_bits(sizeof(xlen), AVL)
else if AVL < 2 * VLMAX then to_bits(sizeof(xlen), (AVL + 1) / 2)
else to_bits(sizeof(xlen), VLMAX);
/* Note: ceil(AVL / 2) ≤ vl ≤ VLMAX when VLMAX < AVL < (2 * VLMAX)
* TODO: configuration support for either using ceil(AVL / 2) or VLMAX
*/
X(rd) = vl;
} else if (rd != 0b00000) then { /* set vl to VLMAX */
let AVL = unsigned(ones(sizeof(xlen)));
vl = to_bits(sizeof(xlen), VLMAX);
X(rd) = vl;
} else { /* keep existing vl */
let AVL = unsigned(vl);
let ratio_pow_new = SEW_pow_new - LMUL_pow_new;
if (ratio_pow_new != ratio_pow_ori) then {
/* Note: Implementations can set vill or trap if the vtype setting is not supported.
* TODO: configuration support for both solutions
*/
vtype.bits = 0b1 @ zeros(sizeof(xlen) - 1); /* set vtype.vill */
vl = zeros();
}
};
print_reg("CSR vtype <- " ^ BitStr(vtype.bits));
print_reg("CSR vl <- " ^ BitStr(vl));
/* reset vstart to 0 */
vstart = zeros();
print_reg("CSR vstart <- " ^ BitStr(vstart));
RETIRE_SUCCESS
}
mapping vsettype_mnemonic : vsetop <-> string ={
VSETVLI <-> "vsetvli",
VSETVL <-> "vsetvli"
}
mapping clause assembly = VSET_TYPE(op, ma, ta, sew, lmul, rs1, rd)
<-> vsettype_mnemonic(op) ^ spc() ^ reg_name(rd) ^ sep() ^ reg_name(rs1) ^ sep() ^ sew_flag(sew) ^ maybe_lmul_flag(lmul) ^ maybe_ta_flag(ta) ^ maybe_ma_flag(ma)
/* ********************************* vsetivli ************************************ */
union clause ast = VSETI_TYPE : ( bits(1), bits(1), bits(3), bits(3), regidx, regidx)
mapping clause encdec = VSETI_TYPE(ma, ta, sew, lmul, uimm, rd) if haveVExt()
<-> 0b1100 @ ma @ ta @ sew @ lmul @ uimm @ 0b111 @ rd @ 0b1010111 if haveVExt()
function clause execute VSETI_TYPE(ma, ta, sew, lmul, uimm, rd) = {
let VLEN_pow = get_vlen_pow();
let ELEN_pow = get_elen_pow();
let LMUL_pow_ori = get_lmul_pow();
let SEW_pow_ori = get_sew_pow();
let ratio_pow_ori = SEW_pow_ori - LMUL_pow_ori;
/* set vtype */
vtype.bits = 0b0 @ zeros(sizeof(xlen) - 9) @ ma @ ta @ sew @ lmul;
/* check legal SEW and LMUL and calculate VLMAX */
let LMUL_pow_new = get_lmul_pow();
let SEW_pow_new = get_sew_pow();
if SEW_pow_new > LMUL_pow_new + ELEN_pow then {
/* Note: Implementations can set vill or trap if the vtype setting is not supported.
* TODO: configuration support for both solutions
*/
vtype.bits = 0b1 @ zeros(sizeof(xlen) - 1); /* set vtype.vill */
vl = zeros();
print_reg("CSR vtype <- " ^ BitStr(vtype.bits));
print_reg("CSR vl <- " ^ BitStr(vl));
return RETIRE_SUCCESS
};
let VLMAX = int_power(2, VLEN_pow + LMUL_pow_new - SEW_pow_new);
let AVL = unsigned(uimm); /* AVL is encoded as 5-bit zero-extended imm in the rs1 field */
/* set vl according to VLMAX and AVL */
vl = if AVL <= VLMAX then to_bits(sizeof(xlen), AVL)
else if AVL < 2 * VLMAX then to_bits(sizeof(xlen), (AVL + 1) / 2)
else to_bits(sizeof(xlen), VLMAX);
/* Note: ceil(AVL / 2) ≤ vl ≤ VLMAX when VLMAX < AVL < (2 * VLMAX)
* TODO: configuration support for either using ceil(AVL / 2) or VLMAX
*/
X(rd) = vl;
print_reg("CSR vtype <- " ^ BitStr(vtype.bits));
print_reg("CSR vl <- " ^ BitStr(vl));
/* reset vstart to 0 */
vstart = zeros();
print_reg("CSR vstart <- " ^ BitStr(vstart));
RETIRE_SUCCESS
}
mapping clause assembly = VSETI_TYPE(ma, ta, sew, lmul, uimm, rd)
<-> "vsetivli" ^ spc() ^ reg_name(rd) ^ sep() ^ hex_bits_5(uimm) ^ sep() ^ sew_flag(sew) ^ maybe_lmul_flag(lmul) ^ maybe_ta_flag(ta) ^ maybe_ma_flag(ma)
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