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FPU: Implement remaining FPSCR-related instructions

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This implements mcrfs, mtfsfi, mtfsb0/1, mffscr, mffscrn, mffscrni and
mffsl.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
pull/245/head
Paul Mackerras 4 years ago
parent bf1d9e9531
commit fc2968f132
3 changed files with 87 additions and 4 deletions
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4
decode1.vhdl
Unescape Escape View File

@ -422,6 +422,10 @@ architecture behaviour of decode1 is
constant decode_op_63l_array : op_63_subop_array_0_t := (
-- unit internal in1 in2 in3 out CR CR inv inv cry cry ldst BR sgn upd rsrv 32b sgn rc lk sgl
-- op in out A out in out len ext pipe
2#000000010# => (FPU, OP_FPOP, NONE, NONE, NONE, NONE, '0', '1', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '0'), -- 2/0=mcrfs
2#011000001# => (FPU, OP_FPOP, NONE, NONE, NONE, NONE, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', RC, '0', '0'), -- 1/6=mtfsb1
2#011000010# => (FPU, OP_FPOP, NONE, NONE, NONE, NONE, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', RC, '0', '0'), -- 2/6=mtfsb0
2#011000100# => (FPU, OP_FPOP, NONE, NONE, NONE, NONE, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', RC, '0', '0'), -- 4/6=mtfsfi
2#011110010# => (FPU, OP_FPOP_I, NONE, FRB, NONE, FRT, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', RC, '0', '0'), -- 18/7=mffs family
2#011110110# => (FPU, OP_FPOP_I, NONE, FRB, NONE, NONE, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', RC, '0', '0'), -- 22/7=mtfsf
others => illegal_inst

79
fpu.vhdl
Unescape Escape View File

@ -26,7 +26,7 @@ end entity fpu;
architecture behaviour of fpu is

type state_t is (IDLE,
DO_MFFS, DO_MTFSF);
DO_MCRFS, DO_MTFSB, DO_MTFSFI, DO_MFFS, DO_MTFSF);

type reg_type is record
state : state_t;
@ -42,6 +42,7 @@ architecture behaviour of fpu is
single_prec : std_ulogic;
fpscr : std_ulogic_vector(31 downto 0);
b : std_ulogic_vector(63 downto 0);
r : std_ulogic_vector(63 downto 0);
writing_back : std_ulogic;
cr_result : std_ulogic_vector(3 downto 0);
cr_mask : std_ulogic_vector(7 downto 0);
@ -77,13 +78,14 @@ begin
w_out.write_enable <= r.writing_back;
w_out.write_reg <= r.dest_fpr;
w_out.write_data <= fp_result;
w_out.write_cr_enable <= r.instr_done and r.rc;
w_out.write_cr_enable <= r.instr_done and (r.rc or r.is_cmp);
w_out.write_cr_mask <= r.cr_mask;
w_out.write_cr_data <= r.cr_result & r.cr_result & r.cr_result & r.cr_result &
r.cr_result & r.cr_result & r.cr_result & r.cr_result;

fpu_1: process(all)
variable v : reg_type;
variable fpscr_mask : std_ulogic_vector(31 downto 0);
variable illegal : std_ulogic;
variable j, k : integer;
variable flm : std_ulogic_vector(7 downto 0);
@ -101,17 +103,30 @@ begin
v.single_prec := e_in.single;
v.rc := e_in.rc;
v.is_cmp := e_in.out_cr;
if e_in.out_cr = '0' then
v.cr_mask := num_to_fxm(1);
else
v.cr_mask := num_to_fxm(to_integer(unsigned(insn_bf(e_in.insn))));
end if;
v.b := e_in.frb;
end if;

v.writing_back := '0';
v.instr_done := '0';
fpscr_mask := (others => '1');

case r.state is
when IDLE =>
if e_in.valid = '1' then
case e_in.insn(5 downto 1) is
when "00000" =>
v.state := DO_MCRFS;
when "00110" =>
if e_in.insn(8) = '0' then
v.state := DO_MTFSB;
else
v.state := DO_MTFSFI;
end if;
when "00111" =>
if e_in.insn(8) = '0' then
v.state := DO_MFFS;
@ -123,11 +138,67 @@ begin
end case;
end if;

when DO_MCRFS =>
j := to_integer(unsigned(insn_bfa(r.insn)));
for i in 0 to 7 loop
if i = j then
k := (7 - i) * 4;
v.cr_result := r.fpscr(k + 3 downto k);
fpscr_mask(k + 3 downto k) := "0000";
end if;
end loop;
v.fpscr := r.fpscr and (fpscr_mask or x"6007F8FF");
v.instr_done := '1';
v.state := IDLE;

when DO_MTFSB =>
-- mtfsb{0,1}
j := to_integer(unsigned(insn_bt(r.insn)));
for i in 0 to 31 loop
if i = j then
v.fpscr(31 - i) := r.insn(6);
end if;
end loop;
v.instr_done := '1';
v.state := IDLE;

when DO_MTFSFI =>
-- mtfsfi
j := to_integer(unsigned(insn_bf(r.insn)));
if r.insn(16) = '0' then
for i in 0 to 7 loop
if i = j then
k := (7 - i) * 4;
v.fpscr(k + 3 downto k) := insn_u(r.insn);
end if;
end loop;
end if;
v.instr_done := '1';
v.state := IDLE;

when DO_MFFS =>
v.writing_back := '1';
case r.insn(20 downto 16) is
when "00000" =>
-- mffs
when "00001" =>
-- mffsce
v.fpscr(FPSCR_VE downto FPSCR_XE) := "00000";
when "10100" | "10101" =>
-- mffscdrn[i] (but we don't implement DRN)
fpscr_mask := x"000000FF";
when "10110" =>
-- mffscrn
fpscr_mask := x"000000FF";
v.fpscr(FPSCR_RN+1 downto FPSCR_RN) :=
r.b(FPSCR_RN+1 downto FPSCR_RN);
when "10111" =>
-- mffscrni
fpscr_mask := x"000000FF";
v.fpscr(FPSCR_RN+1 downto FPSCR_RN) := r.insn(12 downto 11);
when "11000" =>
-- mffsl
fpscr_mask := x"0007F0FF";
when others =>
illegal := '1';
end case;
@ -155,7 +226,9 @@ begin

-- Data path.
-- Just enough to read FPSCR for now.
fp_result <= x"00000000" & r.fpscr;
v.r := x"00000000" & (r.fpscr and fpscr_mask);

fp_result <= r.r;

v.fpscr(FPSCR_VX) := (or (v.fpscr(FPSCR_VXSNAN downto FPSCR_VXVC))) or
(or (v.fpscr(FPSCR_VXSOFT downto FPSCR_VXCVI)));

6
insn_helpers.vhdl
Unescape Escape View File

@ -41,6 +41,7 @@ package insn_helpers is
function insn_fra (insn_in : std_ulogic_vector) return std_ulogic_vector;
function insn_frb (insn_in : std_ulogic_vector) return std_ulogic_vector;
function insn_frc (insn_in : std_ulogic_vector) return std_ulogic_vector;
function insn_u (insn_in : std_ulogic_vector) return std_ulogic_vector;
end package insn_helpers;

package body insn_helpers is
@ -238,4 +239,9 @@ package body insn_helpers is
begin
return insn_in(10 downto 6);
end;

function insn_u(insn_in : std_ulogic_vector) return std_ulogic_vector is
begin
return insn_in(15 downto 12);
end;
end package body insn_helpers;

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