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A tiny Open POWER ISA softcore written in VHDL 2008
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microwatt/loadstore1.vhdl

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library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
library work;
use work.decode_types.all;
use work.common.all;
use work.insn_helpers.all;
use work.helpers.all;
-- 2 cycle LSU
-- We calculate the address in the first cycle
entity loadstore1 is
generic (
HAS_FPU : boolean := true;
-- Non-zero to enable log data collection
LOG_LENGTH : natural := 0
);
port (
clk : in std_ulogic;
rst : in std_ulogic;
l_in : in Execute1ToLoadstore1Type;
e_out : out Loadstore1ToExecute1Type;
l_out : out Loadstore1ToWritebackType;
d_out : out Loadstore1ToDcacheType;
d_in : in DcacheToLoadstore1Type;
m_out : out Loadstore1ToMmuType;
m_in : in MmuToLoadstore1Type;
dc_stall : in std_ulogic;
events : out Loadstore1EventType;
-- Access to SPRs from core_debug module
dbg_spr_req : in std_ulogic;
dbg_spr_ack : out std_ulogic;
dbg_spr_addr : in std_ulogic_vector(1 downto 0);
dbg_spr_data : out std_ulogic_vector(63 downto 0);
log_out : out std_ulogic_vector(9 downto 0)
);
end loadstore1;
architecture behave of loadstore1 is
-- State machine for unaligned loads/stores
type state_t is (IDLE, -- ready for instruction
MMU_WAIT -- waiting for MMU to finish doing something
);
type byte_index_t is array(0 to 7) of unsigned(2 downto 0);
subtype byte_trim_t is std_ulogic_vector(1 downto 0);
type trim_ctl_t is array(0 to 7) of byte_trim_t;
type request_t is record
valid : std_ulogic;
dc_req : std_ulogic;
load : std_ulogic;
store : std_ulogic;
tlbie : std_ulogic;
dcbz : std_ulogic;
read_spr : std_ulogic;
write_spr : std_ulogic;
mmu_op : std_ulogic;
instr_fault : std_ulogic;
do_update : std_ulogic;
mode_32bit : std_ulogic;
addr : std_ulogic_vector(63 downto 0);
byte_sel : std_ulogic_vector(7 downto 0);
second_bytes : std_ulogic_vector(7 downto 0);
store_data : std_ulogic_vector(63 downto 0);
instr_tag : instr_tag_t;
write_reg : gspr_index_t;
length : std_ulogic_vector(3 downto 0);
elt_length : std_ulogic_vector(3 downto 0);
byte_reverse : std_ulogic;
brev_mask : unsigned(2 downto 0);
sign_extend : std_ulogic;
update : std_ulogic;
xerc : xer_common_t;
reserve : std_ulogic;
rc : std_ulogic;
nc : std_ulogic; -- non-cacheable access
virt_mode : std_ulogic;
priv_mode : std_ulogic;
load_sp : std_ulogic;
sprsel : std_ulogic_vector(1 downto 0);
ric : std_ulogic_vector(1 downto 0);
is_slbia : std_ulogic;
align_intr : std_ulogic;
dword_index : std_ulogic;
two_dwords : std_ulogic;
incomplete : std_ulogic;
end record;
constant request_init : request_t := (valid => '0', dc_req => '0', load => '0', store => '0', tlbie => '0',
dcbz => '0', read_spr => '0', write_spr => '0', mmu_op => '0',
instr_fault => '0', do_update => '0',
mode_32bit => '0', addr => (others => '0'),
byte_sel => x"00", second_bytes => x"00",
store_data => (others => '0'), instr_tag => instr_tag_init,
write_reg => 6x"00", length => x"0",
elt_length => x"0", byte_reverse => '0', brev_mask => "000",
sign_extend => '0', update => '0',
xerc => xerc_init, reserve => '0',
rc => '0', nc => '0',
virt_mode => '0', priv_mode => '0', load_sp => '0',
sprsel => "00", ric => "00", is_slbia => '0', align_intr => '0',
dword_index => '0', two_dwords => '0', incomplete => '0');
type reg_stage1_t is record
req : request_t;
busy : std_ulogic;
issued : std_ulogic;
addr0 : std_ulogic_vector(63 downto 0);
end record;
type reg_stage2_t is record
req : request_t;
byte_index : byte_index_t;
use_second : std_ulogic_vector(7 downto 0);
busy : std_ulogic;
wait_dc : std_ulogic;
wait_mmu : std_ulogic;
one_cycle : std_ulogic;
wr_sel : std_ulogic_vector(1 downto 0);
addr0 : std_ulogic_vector(63 downto 0);
sprsel : std_ulogic_vector(1 downto 0);
dbg_spr : std_ulogic_vector(63 downto 0);
dbg_spr_ack: std_ulogic;
end record;
type reg_stage3_t is record
state : state_t;
complete : std_ulogic;
instr_tag : instr_tag_t;
write_enable : std_ulogic;
write_reg : gspr_index_t;
write_data : std_ulogic_vector(63 downto 0);
rc : std_ulogic;
xerc : xer_common_t;
store_done : std_ulogic;
load_data : std_ulogic_vector(63 downto 0);
dar : std_ulogic_vector(63 downto 0);
dsisr : std_ulogic_vector(31 downto 0);
ld_sp_data : std_ulogic_vector(31 downto 0);
ld_sp_nz : std_ulogic;
ld_sp_lz : std_ulogic_vector(5 downto 0);
stage1_en : std_ulogic;
interrupt : std_ulogic;
intr_vec : integer range 0 to 16#fff#;
srr1 : std_ulogic_vector(15 downto 0);
events : Loadstore1EventType;
end record;
signal req_in : request_t;
signal r1, r1in : reg_stage1_t;
signal r2, r2in : reg_stage2_t;
signal r3, r3in : reg_stage3_t;
signal flush : std_ulogic;
signal busy : std_ulogic;
signal complete : std_ulogic;
signal flushing : std_ulogic;
signal store_sp_data : std_ulogic_vector(31 downto 0);
signal load_dp_data : std_ulogic_vector(63 downto 0);
signal store_data : std_ulogic_vector(63 downto 0);
signal stage1_req : request_t;
signal stage1_dcreq : std_ulogic;
signal stage1_dreq : std_ulogic;
-- Generate byte enables from sizes
function length_to_sel(length : in std_logic_vector(3 downto 0)) return std_ulogic_vector is
begin
case length is
when "0001" =>
return "00000001";
when "0010" =>
return "00000011";
when "0100" =>
return "00001111";
when "1000" =>
return "11111111";
when others =>
return "00000000";
end case;
end function length_to_sel;
-- Calculate byte enables
-- This returns 16 bits, giving the select signals for two transfers,
-- to account for unaligned loads or stores
function xfer_data_sel(size : in std_logic_vector(3 downto 0);
address : in std_logic_vector(2 downto 0))
return std_ulogic_vector is
variable longsel : std_ulogic_vector(15 downto 0);
begin
if is_X(address) then
longsel := (others => 'X');
return longsel;
else
longsel := "00000000" & length_to_sel(size);
return std_ulogic_vector(shift_left(unsigned(longsel),
to_integer(unsigned(address))));
end if;
end function xfer_data_sel;
-- 23-bit right shifter for DP -> SP float conversions
function shifter_23r(frac: std_ulogic_vector(22 downto 0); shift: unsigned(4 downto 0))
return std_ulogic_vector is
variable fs1 : std_ulogic_vector(22 downto 0);
variable fs2 : std_ulogic_vector(22 downto 0);
begin
case shift(1 downto 0) is
when "00" =>
fs1 := frac;
when "01" =>
fs1 := '0' & frac(22 downto 1);
when "10" =>
fs1 := "00" & frac(22 downto 2);
when others =>
fs1 := "000" & frac(22 downto 3);
end case;
case shift(4 downto 2) is
when "000" =>
fs2 := fs1;
when "001" =>
fs2 := x"0" & fs1(22 downto 4);
when "010" =>
fs2 := x"00" & fs1(22 downto 8);
when "011" =>
fs2 := x"000" & fs1(22 downto 12);
when "100" =>
fs2 := x"0000" & fs1(22 downto 16);
when others =>
fs2 := x"00000" & fs1(22 downto 20);
end case;
return fs2;
end;
-- 23-bit left shifter for SP -> DP float conversions
function shifter_23l(frac: std_ulogic_vector(22 downto 0); shift: unsigned(4 downto 0))
return std_ulogic_vector is
variable fs1 : std_ulogic_vector(22 downto 0);
variable fs2 : std_ulogic_vector(22 downto 0);
begin
case shift(1 downto 0) is
when "00" =>
fs1 := frac;
when "01" =>
fs1 := frac(21 downto 0) & '0';
when "10" =>
fs1 := frac(20 downto 0) & "00";
when others =>
fs1 := frac(19 downto 0) & "000";
end case;
case shift(4 downto 2) is
when "000" =>
fs2 := fs1;
when "001" =>
fs2 := fs1(18 downto 0) & x"0" ;
when "010" =>
fs2 := fs1(14 downto 0) & x"00";
when "011" =>
fs2 := fs1(10 downto 0) & x"000";
when "100" =>
fs2 := fs1(6 downto 0) & x"0000";
when others =>
fs2 := fs1(2 downto 0) & x"00000";
end case;
return fs2;
end;
begin
loadstore1_reg: process(clk)
begin
if rising_edge(clk) then
if rst = '1' then
r1.busy <= '0';
r1.issued <= '0';
r1.req.valid <= '0';
r1.req.dc_req <= '0';
r1.req.incomplete <= '0';
r1.req.tlbie <= '0';
r1.req.is_slbia <= '0';
r1.req.instr_fault <= '0';
r1.req.load <= '0';
r1.req.priv_mode <= '0';
r1.req.sprsel <= "00";
r1.req.ric <= "00";
r1.req.xerc <= xerc_init;
r2.req.valid <= '0';
r2.busy <= '0';
r2.req.tlbie <= '0';
r2.req.is_slbia <= '0';
r2.req.instr_fault <= '0';
r2.req.load <= '0';
r2.req.priv_mode <= '0';
r2.req.sprsel <= "00";
r2.req.ric <= "00";
r2.req.xerc <= xerc_init;
r2.wait_dc <= '0';
r2.wait_mmu <= '0';
r2.one_cycle <= '0';
r3.dar <= (others => '0');
r3.dsisr <= (others => '0');
r3.state <= IDLE;
r3.write_enable <= '0';
r3.interrupt <= '0';
r3.complete <= '0';
r3.stage1_en <= '1';
r3.events.load_complete <= '0';
r3.events.store_complete <= '0';
flushing <= '0';
else
r1 <= r1in;
r2 <= r2in;
r3 <= r3in;
flushing <= (flushing or (r1in.req.valid and r1in.req.align_intr)) and
not flush;
end if;
stage1_dreq <= stage1_dcreq;
if d_in.valid = '1' then
assert r2.req.valid = '1' and r2.req.dc_req = '1' and r3.state = IDLE severity failure;
end if;
if d_in.error = '1' then
assert r2.req.valid = '1' and r2.req.dc_req = '1' and r3.state = IDLE severity failure;
end if;
if m_in.done = '1' or m_in.err = '1' then
assert r2.req.valid = '1' and r3.state = MMU_WAIT severity failure;
end if;
end if;
end process;
ls_fp_conv: if HAS_FPU generate
-- Convert DP data to SP for stfs
dp_to_sp: process(all)
variable exp : unsigned(10 downto 0);
variable frac : std_ulogic_vector(22 downto 0);
variable shift : unsigned(4 downto 0);
begin
store_sp_data(31) <= l_in.data(63);
store_sp_data(30 downto 0) <= (others => '0');
exp := unsigned(l_in.data(62 downto 52));
if exp > 896 then
store_sp_data(30) <= l_in.data(62);
store_sp_data(29 downto 0) <= l_in.data(58 downto 29);
elsif exp >= 874 then
-- denormalization required
frac := '1' & l_in.data(51 downto 30);
shift := 0 - exp(4 downto 0);
store_sp_data(22 downto 0) <= shifter_23r(frac, shift);
end if;
end process;
-- Convert SP data to DP for lfs
sp_to_dp: process(all)
variable exp : unsigned(7 downto 0);
variable exp_dp : unsigned(10 downto 0);
variable exp_nz : std_ulogic;
variable exp_ao : std_ulogic;
variable frac : std_ulogic_vector(22 downto 0);
variable frac_shift : unsigned(4 downto 0);
begin
frac := r3.ld_sp_data(22 downto 0);
exp := unsigned(r3.ld_sp_data(30 downto 23));
exp_nz := or (r3.ld_sp_data(30 downto 23));
exp_ao := and (r3.ld_sp_data(30 downto 23));
frac_shift := (others => '0');
if exp_ao = '1' then
exp_dp := to_unsigned(2047, 11); -- infinity or NaN
elsif exp_nz = '1' then
exp_dp := 896 + resize(exp, 11); -- finite normalized value
elsif r3.ld_sp_nz = '0' then
exp_dp := to_unsigned(0, 11); -- zero
else
-- denormalized SP operand, need to normalize
exp_dp := 896 - resize(unsigned(r3.ld_sp_lz), 11);
frac_shift := unsigned(r3.ld_sp_lz(4 downto 0)) + 1;
end if;
load_dp_data(63) <= r3.ld_sp_data(31);
load_dp_data(62 downto 52) <= std_ulogic_vector(exp_dp);
load_dp_data(51 downto 29) <= shifter_23l(frac, frac_shift);
load_dp_data(28 downto 0) <= (others => '0');
end process;
end generate;
-- Translate a load/store instruction into the internal request format
-- XXX this should only depend on l_in, but actually depends on
-- r1.addr0 as well (in the l_in.second = 1 case).
loadstore1_in: process(all)
variable v : request_t;
variable lsu_sum : std_ulogic_vector(63 downto 0);
variable brev_lenm1 : unsigned(2 downto 0);
variable long_sel : std_ulogic_vector(15 downto 0);
variable addr : std_ulogic_vector(63 downto 0);
variable sprn : std_ulogic_vector(9 downto 0);
variable misaligned : std_ulogic;
variable addr_mask : std_ulogic_vector(2 downto 0);
begin
v := request_init;
sprn := l_in.insn(15 downto 11) & l_in.insn(20 downto 16);
v.valid := l_in.valid;
v.instr_tag := l_in.instr_tag;
v.mode_32bit := l_in.mode_32bit;
v.write_reg := l_in.write_reg;
v.length := l_in.length;
v.elt_length := l_in.length;
v.byte_reverse := l_in.byte_reverse;
v.sign_extend := l_in.sign_extend;
v.update := l_in.update;
v.xerc := l_in.xerc;
v.reserve := l_in.reserve;
v.rc := l_in.rc;
v.nc := l_in.ci;
v.virt_mode := l_in.virt_mode;
v.priv_mode := l_in.priv_mode;
v.ric := l_in.insn(19 downto 18);
if sprn(1) = '1' then
-- DSISR and DAR
v.sprsel := '1' & sprn(0);
else
-- PID and PTCR
v.sprsel := '0' & sprn(8);
end if;
lsu_sum := std_ulogic_vector(unsigned(l_in.addr1) + unsigned(l_in.addr2));
if HAS_FPU and l_in.is_32bit = '1' then
v.store_data := x"00000000" & store_sp_data;
else
v.store_data := l_in.data;
end if;
addr := lsu_sum;
if l_in.second = '1' then
-- for an update-form load, use the previous address
-- as the value to write back to RA.
addr := r1.addr0;
end if;
if l_in.mode_32bit = '1' then
addr(63 downto 32) := (others => '0');
end if;
v.addr := addr;
-- XXX Temporary hack. Mark the op as non-cachable if the address
-- is the form 0xc------- for a real-mode access.
if addr(31 downto 28) = "1100" and l_in.virt_mode = '0' then
v.nc := '1';
end if;
addr_mask := std_ulogic_vector(unsigned(l_in.length(2 downto 0)) - 1);
-- Do length_to_sel and work out if we are doing 2 dwords
long_sel := xfer_data_sel(v.length, addr(2 downto 0));
v.byte_sel := long_sel(7 downto 0);
v.second_bytes := long_sel(15 downto 8);
if long_sel(15 downto 8) /= "00000000" then
v.two_dwords := '1';
end if;
-- check alignment for larx/stcx
misaligned := or (addr_mask and addr(2 downto 0));
v.align_intr := l_in.reserve and misaligned;
case l_in.op is
when OP_STORE =>
v.store := '1';
when OP_LOAD =>
-- Note: only RA updates have l_in.second = 1
if l_in.second = '0' then
v.load := '1';
if HAS_FPU and l_in.is_32bit = '1' then
-- Allow an extra cycle for SP->DP precision conversion
v.load_sp := '1';
end if;
else
-- write back address to RA
v.do_update := '1';
end if;
when OP_DCBZ =>
v.dcbz := '1';
v.align_intr := v.nc;
when OP_TLBIE =>
v.tlbie := '1';
v.addr := l_in.addr2; -- address from RB for tlbie
v.is_slbia := l_in.insn(7);
v.mmu_op := '1';
when OP_MFSPR =>
v.read_spr := '1';
when OP_MTSPR =>
v.write_spr := '1';
v.mmu_op := not sprn(1);
when OP_FETCH_FAILED =>
-- send it to the MMU to do the radix walk
v.instr_fault := '1';
v.mmu_op := '1';
when others =>
end case;
v.dc_req := l_in.valid and (v.load or v.store or v.dcbz) and not v.align_intr;
v.incomplete := v.dc_req and v.two_dwords;
-- Work out controls for load and store formatting
brev_lenm1 := "000";
if v.byte_reverse = '1' then
brev_lenm1 := unsigned(v.length(2 downto 0)) - 1;
end if;
v.brev_mask := brev_lenm1;
req_in <= v;
end process;
busy <= dc_stall or d_in.error or r1.busy or r2.busy;
complete <= r2.one_cycle or (r2.wait_dc and d_in.valid) or r3.complete;
-- Processing done in the first cycle of a load/store instruction
loadstore1_1: process(all)
variable v : reg_stage1_t;
variable req : request_t;
variable dcreq : std_ulogic;
variable issue : std_ulogic;
begin
v := r1;
issue := '0';
dcreq := '0';
if r1.busy = '0' then
req := req_in;
req.valid := l_in.valid;
if flushing = '1' then
-- Make this a no-op request rather than simply invalid.
-- It will never get to stage 3 since there is a request ahead of
-- it with align_intr = 1.
req.dc_req := '0';
end if;
issue := l_in.valid and req.dc_req;
if l_in.valid = '1' then
v.addr0 := req.addr;
end if;
else
req := r1.req;
if r1.req.dc_req = '1' and r1.issued = '0' then
issue := '1';
elsif r1.req.incomplete = '1' then
-- construct the second request for a misaligned access
req.dword_index := '1';
req.incomplete := '0';
req.addr := std_ulogic_vector(unsigned(r1.req.addr(63 downto 3)) + 1) & "000";
if r1.req.mode_32bit = '1' then
req.addr(32) := '0';
end if;
req.byte_sel := r1.req.second_bytes;
issue := '1';
else
-- For the lfs conversion cycle, leave the request valid
-- for another cycle but with req.dc_req = 0.
-- For an MMU request last cycle, we have nothing
-- to do in this cycle, so make it invalid.
if r1.req.load_sp = '0' then
req.valid := '0';
end if;
req.dc_req := '0';
end if;
end if;
if flush = '1' then
v.req.valid := '0';
v.req.dc_req := '0';
v.req.incomplete := '0';
v.issued := '0';
v.busy := '0';
elsif (dc_stall or d_in.error or r2.busy) = '0' then
-- we can change what's in r1 next cycle because the current thing
-- in r1 will go into r2
v.req := req;
dcreq := issue;
v.issued := issue;
v.busy := (issue and (req.incomplete or req.load_sp)) or (req.valid and req.mmu_op);
else
-- pipeline is stalled
if r1.issued = '1' and d_in.error = '1' then
v.issued := '0';
v.busy := '1';
end if;
end if;
stage1_req <= req;
stage1_dcreq <= dcreq;
r1in <= v;
end process;
-- Processing done in the second cycle of a load/store instruction.
-- Store data is formatted here and sent to the dcache.
-- The request in r1 is sent to stage 3 if stage 3 will not be busy next cycle.
loadstore1_2: process(all)
variable v : reg_stage2_t;
variable j : integer;
variable k : unsigned(2 downto 0);
variable kk : unsigned(3 downto 0);
variable idx : unsigned(2 downto 0);
variable byte_offset : unsigned(2 downto 0);
variable interrupt : std_ulogic;
variable dbg_spr_rd : std_ulogic;
variable sprsel : std_ulogic_vector(1 downto 0);
variable sprval : std_ulogic_vector(63 downto 0);
begin
v := r2;
-- Byte reversing and rotating for stores.
-- Done in the second cycle (the cycle after l_in.valid = 1).
byte_offset := unsigned(r1.addr0(2 downto 0));
for i in 0 to 7 loop
k := (to_unsigned(i, 3) - byte_offset) xor r1.req.brev_mask;
if is_X(k) then
store_data(i * 8 + 7 downto i * 8) <= (others => 'X');
else
j := to_integer(k) * 8;
store_data(i * 8 + 7 downto i * 8) <= r1.req.store_data(j + 7 downto j);
end if;
end loop;
dbg_spr_rd := dbg_spr_req and not (r1.req.valid and r1.req.read_spr);
if dbg_spr_rd = '0' then
sprsel := r1.req.sprsel;
else
sprsel := dbg_spr_addr;
end if;
if sprsel(1) = '1' then
if sprsel(0) = '0' then
sprval := x"00000000" & r3.dsisr;
else
sprval := r3.dar;
end if;
else
sprval := m_in.sprval;
end if;
if dbg_spr_req = '0' then
v.dbg_spr_ack := '0';
elsif dbg_spr_rd = '1' and r2.dbg_spr_ack = '0' then
v.dbg_spr := sprval;
v.dbg_spr_ack := '1';
end if;
if (dc_stall or d_in.error or r2.busy or l_in.e2stall) = '0' then
if r1.req.valid = '0' or r1.issued = '1' or r1.req.dc_req = '0' then
v.req := r1.req;
v.addr0 := r1.addr0;
v.req.store_data := store_data;
v.wait_dc := r1.req.valid and r1.req.dc_req and not r1.req.load_sp and
not r1.req.incomplete;
v.wait_mmu := r1.req.valid and r1.req.mmu_op;
v.busy := r1.req.valid and r1.req.mmu_op;
v.one_cycle := r1.req.valid and not (r1.req.dc_req or r1.req.mmu_op);
if r1.req.do_update = '1' or r1.req.store = '1' or r1.req.read_spr = '1' then
v.wr_sel := "00";
elsif r1.req.load_sp = '1' then
v.wr_sel := "01";
else
v.wr_sel := "10";
end if;
if r1.req.read_spr = '1' then
v.addr0 := sprval;
end if;
-- Work out load formatter controls for next cycle
for i in 0 to 7 loop
idx := to_unsigned(i, 3) xor r1.req.brev_mask;
kk := ('0' & idx) + ('0' & byte_offset);
v.use_second(i) := kk(3);
v.byte_index(i) := kk(2 downto 0);
end loop;
else
v.req.valid := '0';
v.wait_dc := '0';
v.wait_mmu := '0';
v.one_cycle := '0';
end if;
end if;
if r2.wait_mmu = '1' and m_in.done = '1' then
if r2.req.mmu_op = '1' then
v.req.valid := '0';
v.busy := '0';
end if;
v.wait_mmu := '0';
end if;
if r2.busy = '1' and r2.wait_mmu = '0' then
v.busy := '0';
end if;
interrupt := (r2.req.valid and r2.req.align_intr) or
(d_in.error and d_in.cache_paradox) or m_in.err;
if interrupt = '1' then
v.req.valid := '0';
v.busy := '0';
v.wait_dc := '0';
v.wait_mmu := '0';
elsif d_in.error = '1' then
v.wait_mmu := '1';
v.busy := '1';
end if;
r2in <= v;
-- SPR values for core_debug
dbg_spr_data <= r2.dbg_spr;
dbg_spr_ack <= r2.dbg_spr_ack;
end process;
-- Processing done in the third cycle of a load/store instruction.
-- At this stage we can do things that have side effects without
-- fear of the instruction getting flushed. This is the point at
-- which requests get sent to the MMU.
loadstore1_3: process(all)
variable v : reg_stage3_t;
variable j : integer;
variable req : std_ulogic;
variable mmureq : std_ulogic;
variable mmu_mtspr : std_ulogic;
variable write_enable : std_ulogic;
variable write_data : std_ulogic_vector(63 downto 0);
variable do_update : std_ulogic;
variable done : std_ulogic;
variable exception : std_ulogic;
variable data_permuted : std_ulogic_vector(63 downto 0);
variable data_trimmed : std_ulogic_vector(63 downto 0);
variable sprval : std_ulogic_vector(63 downto 0);
variable negative : std_ulogic;
variable dsisr : std_ulogic_vector(31 downto 0);
variable itlb_fault : std_ulogic;
variable trim_ctl : trim_ctl_t;
begin
v := r3;
req := '0';
mmureq := '0';
mmu_mtspr := '0';
done := '0';
exception := '0';
dsisr := (others => '0');
write_enable := '0';
sprval := (others => '0');
do_update := '0';
v.complete := '0';
v.srr1 := (others => '0');
v.events := (others => '0');
-- load data formatting
-- shift and byte-reverse data bytes
for i in 0 to 7 loop
if is_X(r2.byte_index(i)) then
data_permuted(i * 8 + 7 downto i * 8) := (others => 'X');
else
j := to_integer(r2.byte_index(i)) * 8;
data_permuted(i * 8 + 7 downto i * 8) := d_in.data(j + 7 downto j);
end if;
end loop;
-- Work out the sign bit for sign extension.
-- For unaligned loads crossing two dwords, the sign bit is in the
-- first dword for big-endian (byte_reverse = 1), or the second dword
-- for little-endian.
if r2.req.dword_index = '1' and r2.req.byte_reverse = '1' then
negative := (r2.req.length(3) and r3.load_data(63)) or
(r2.req.length(2) and r3.load_data(31)) or
(r2.req.length(1) and r3.load_data(15)) or
(r2.req.length(0) and r3.load_data(7));
else
negative := (r2.req.length(3) and data_permuted(63)) or
(r2.req.length(2) and data_permuted(31)) or
(r2.req.length(1) and data_permuted(15)) or
(r2.req.length(0) and data_permuted(7));
end if;
-- trim and sign-extend
for i in 0 to 7 loop
if is_X(r2.req.length) then
trim_ctl(i) := "XX";
elsif i < to_integer(unsigned(r2.req.length)) then
if r2.req.dword_index = '1' then
trim_ctl(i) := '1' & not r2.use_second(i);
else
trim_ctl(i) := "10";
end if;
else
trim_ctl(i) := "00";
end if;
end loop;
for i in 0 to 7 loop
case trim_ctl(i) is
when "11" =>
data_trimmed(i * 8 + 7 downto i * 8) := r3.load_data(i * 8 + 7 downto i * 8);
when "10" =>
data_trimmed(i * 8 + 7 downto i * 8) := data_permuted(i * 8 + 7 downto i * 8);
when others =>
data_trimmed(i * 8 + 7 downto i * 8) := (others => negative and r2.req.sign_extend);
end case;
end loop;
if HAS_FPU then
-- Single-precision FP conversion for loads
v.ld_sp_data := data_trimmed(31 downto 0);
v.ld_sp_nz := or (data_trimmed(22 downto 0));
v.ld_sp_lz := count_left_zeroes(data_trimmed(22 downto 0));
end if;
if d_in.valid = '1' and r2.req.load = '1' then
v.load_data := data_permuted;
end if;
if r2.req.valid = '1' then
if r2.req.read_spr = '1' then
write_enable := '1';
end if;
if r2.req.align_intr = '1' then
-- generate alignment interrupt
exception := '1';
end if;
if r2.req.do_update = '1' then
do_update := '1';
end if;
if r2.req.load_sp = '1' and r2.req.dc_req = '0' then
write_enable := '1';
end if;
if r2.req.write_spr = '1' and r2.req.mmu_op = '0' then
if r2.req.sprsel(0) = '0' then
v.dsisr := r2.req.store_data(31 downto 0);
else
v.dar := r2.req.store_data;
end if;
end if;
end if;
if r3.state = IDLE and r2.req.valid = '1' and r2.req.mmu_op = '1' then
-- send request (tlbie, mtspr, itlb miss) to MMU
mmureq := not r2.req.write_spr;
mmu_mtspr := r2.req.write_spr;
if r2.req.instr_fault = '1' then
v.events.itlb_miss := '1';
end if;
v.state := MMU_WAIT;
end if;
if d_in.valid = '1' then
if r2.req.incomplete = '0' then
write_enable := r2.req.load and not r2.req.load_sp;
-- stores write back rA update
do_update := r2.req.update and r2.req.store;
end if;
end if;
if d_in.error = '1' then
if d_in.cache_paradox = '1' then
-- signal an interrupt straight away
exception := '1';
dsisr(63 - 38) := not r2.req.load;
-- XXX there is no architected bit for this
-- (probably should be a machine check in fact)
dsisr(63 - 35) := d_in.cache_paradox;
else
-- Look up the translation for TLB miss
-- and also for permission error and RC error
-- in case the PTE has been updated.
mmureq := '1';
v.state := MMU_WAIT;
v.stage1_en := '0';
end if;
end if;
if m_in.done = '1' then
if r2.req.dc_req = '1' then
-- retry the request now that the MMU has installed a TLB entry
req := '1';
else
v.complete := '1';
end if;
end if;
if m_in.err = '1' then
exception := '1';
dsisr(63 - 33) := m_in.invalid;
dsisr(63 - 36) := m_in.perm_error;
dsisr(63 - 38) := r2.req.store or r2.req.dcbz;
dsisr(63 - 44) := m_in.badtree;
dsisr(63 - 45) := m_in.rc_error;
end if;
if (m_in.done or m_in.err) = '1' then
v.stage1_en := '1';
v.state := IDLE;
end if;
v.events.load_complete := r2.req.load and complete;
v.events.store_complete := (r2.req.store or r2.req.dcbz) and complete;
-- generate DSI or DSegI for load/store exceptions
-- or ISI or ISegI for instruction fetch exceptions
v.interrupt := exception;
if exception = '1' then
if r2.req.align_intr = '1' then
v.intr_vec := 16#600#;
v.dar := r2.req.addr;
elsif r2.req.instr_fault = '0' then
v.dar := r2.req.addr;
if m_in.segerr = '0' then
v.intr_vec := 16#300#;
v.dsisr := dsisr;
else
v.intr_vec := 16#380#;
end if;
else
if m_in.segerr = '0' then
v.srr1(47 - 33) := m_in.invalid;
v.srr1(47 - 35) := m_in.perm_error; -- noexec fault
v.srr1(47 - 44) := m_in.badtree;
v.srr1(47 - 45) := m_in.rc_error;
v.intr_vec := 16#400#;
else
v.intr_vec := 16#480#;
end if;
end if;
end if;
case r2.wr_sel is
when "00" =>
-- update reg
write_data := r2.addr0;
when "01" =>
-- lfs result
write_data := load_dp_data;
when others =>
-- load data
write_data := data_trimmed;
end case;
-- Update outputs to dcache
if r3.stage1_en = '1' then
d_out.valid <= stage1_dcreq;
d_out.load <= stage1_req.load;
d_out.dcbz <= stage1_req.dcbz;
d_out.nc <= stage1_req.nc;
d_out.reserve <= stage1_req.reserve;
d_out.addr <= stage1_req.addr;
d_out.byte_sel <= stage1_req.byte_sel;
d_out.virt_mode <= stage1_req.virt_mode;
d_out.priv_mode <= stage1_req.priv_mode;
else
d_out.valid <= req;
d_out.load <= r2.req.load;
d_out.dcbz <= r2.req.dcbz;
d_out.nc <= r2.req.nc;
d_out.reserve <= r2.req.reserve;
d_out.addr <= r2.req.addr;
d_out.byte_sel <= r2.req.byte_sel;
d_out.virt_mode <= r2.req.virt_mode;
d_out.priv_mode <= r2.req.priv_mode;
end if;
if stage1_dreq = '1' then
d_out.data <= store_data;
else
d_out.data <= r2.req.store_data;
end if;
d_out.hold <= l_in.e2stall;
-- Update outputs to MMU
m_out.valid <= mmureq;
m_out.iside <= r2.req.instr_fault;
m_out.load <= r2.req.load;
m_out.priv <= r2.req.priv_mode;
m_out.tlbie <= r2.req.tlbie;
m_out.ric <= r2.req.ric;
m_out.mtspr <= mmu_mtspr;
m_out.sprnf <= r1.req.sprsel(0);
m_out.sprnt <= r2.req.sprsel(0);
m_out.addr <= r2.req.addr;
m_out.slbia <= r2.req.is_slbia;
m_out.rs <= r2.req.store_data;
-- Update outputs to writeback
l_out.valid <= complete;
l_out.instr_tag <= r2.req.instr_tag;
l_out.write_enable <= write_enable or do_update;
l_out.write_reg <= r2.req.write_reg;
l_out.write_data <= write_data;
l_out.xerc <= r2.req.xerc;
l_out.rc <= r2.req.rc and complete;
l_out.store_done <= d_in.store_done;
l_out.interrupt <= r3.interrupt;
l_out.intr_vec <= r3.intr_vec;
l_out.srr1 <= r3.srr1;
-- update busy signal back to execute1
e_out.busy <= busy;
e_out.l2stall <= dc_stall or d_in.error or r2.busy;
events <= r3.events;
flush <= exception;
-- Update registers
r3in <= v;
end process;
l1_log: if LOG_LENGTH > 0 generate
signal log_data : std_ulogic_vector(9 downto 0);
begin
ls1_log: process(clk)
begin
if rising_edge(clk) then
log_data <= e_out.busy &
l_out.interrupt &
l_out.valid &
m_out.valid &
d_out.valid &
m_in.done &
r2.req.dword_index &
r2.req.valid &
r2.wait_dc &
std_ulogic_vector(to_unsigned(state_t'pos(r3.state), 1));
end if;
end process;
log_out <= log_data;
end generate;
end;