From 815a5e935a18d9840a01b63e75147eff60523e80 Mon Sep 17 00:00:00 2001
From: Roberto Hexsel <roberto@inf.ufpr.br>
Date: Fri, 22 May 2015 10:47:45 -0300
Subject: [PATCH] fixes to trap handling
---
cMIPS/tests/teq_tne.expected | 26 ++---
cMIPS/tests/teq_tne.s | 47 ++++++--
cMIPS/tests/tlt_tlti.expected | 44 ++++---
cMIPS/tests/tlt_tlti.s | 200 ++++++++++++++++++++-----------
cMIPS/tests/tltu_tgeu.expected | 8 +-
cMIPS/tests/tltu_tgeu.s | 68 +++++++----
cMIPS/vhdl/core.vhd | 208 ++++++++++++++++++---------------
cMIPS/vhdl/exception.vhd | 38 +++---
cMIPS/vhdl/packageMemory.vhd | 4 +-
9 files changed, 383 insertions(+), 260 deletions(-)
diff --git a/cMIPS/tests/teq_tne.expected b/cMIPS/tests/teq_tne.expected
index 0b8d7af..6e0ad2c 100644
--- a/cMIPS/tests/teq_tne.expected
+++ b/cMIPS/tests/teq_tne.expected
@@ -3,42 +3,42 @@
00000004
00000006
00000008
-08800034
+34
00000000
00000002
00000004
00000006
00000008
-08800034
+34
00000000
00000002
00000004
00000006
00000008
-08800034
+34
00000004
-08800034
+34
00000003
-08800034
+34
00000002
-08800034
+34
00000001
-08800034
+34
0000000a
00000008
00000006
00000004
-08800034
+34
00000005
-08800034
+34
00000004
-08800034
+34
00000003
-08800034
+34
00000002
-08800034
+34
00000001
-08800034
+34
diff --git a/cMIPS/tests/teq_tne.s b/cMIPS/tests/teq_tne.s
index fc58e32..47c38b4 100644
--- a/cMIPS/tests/teq_tne.s
+++ b/cMIPS/tests/teq_tne.s
@@ -13,10 +13,13 @@
##
_start: nop
li $sp,(x_DATA_BASE_ADDR+x_DATA_MEM_SZ-8) # initialize SP: ramTop-8
- la $k0, main
- mtc0 $k0, cop0_EPC
- ehb
- eret # go into user mode, all else disabled
+
+ la $k0, cop0_STATUS_reset # go into user mode
+ addi $k0, $k0, -2
+ addi $k0, $k0, 0b10000
+ mtc0 $k0, cop0_STATUS
+
+ j main
nop
exit:
_exit: nop # flush pipeline
@@ -38,9 +41,24 @@ _excp_180:
## print CAUSE, reset counter, decrement iteration control
##
mfc0 $k0, cop0_CAUSE
- sw $k0,0($15) # print CAUSE
- li $5,0
- addiu $7,$7,-1 # decrement iteration control
+ andi $k1, $k0, 0x0030
+ srl $k1, $k1, 4
+ addi $k1, $k1, '0'
+ sw $k1, x_IO_ADDR_RANGE($15)
+ andi $k1, $k0, 0x000f # keep only exception code
+ addi $k1, $k1, '0'
+ sw $k1, x_IO_ADDR_RANGE($15) # print CAUSE.exCode
+ li $k1, '\n'
+ sw $k1, x_IO_ADDR_RANGE($15)
+ li $5, 0
+ addiu $7, $7, -1 # decrement iteration control
+
+ mfc0 $k1, cop0_EPC # move EPC forward to next instruction
+ addi $k1, $k1, 4
+ mtc0 $k1, cop0_EPC # move EPC forward to next instruction
+ mfc0 $k0, cop0_STATUS # go back to user mode
+ ori $k0, $k0, 0x0010
+ mtc0 $k0, cop0_STATUS
excp_180ret:
eret
.end _excp_180
@@ -55,11 +73,16 @@ _excp_200:
##
li $28,-1
sw $28, 0($15) # signal exception to std_out
- sw $28, 0($15)
mfc0 $k0, cop0_CAUSE
+ li $k1, 'e'
+ sw $k1, x_IO_ADDR_RANGE($15)
+ li $k1, 'r'
+ sw $k1, x_IO_ADDR_RANGE($15)
+ li $k1, 'r'
+ sw $k1, x_IO_ADDR_RANGE($15)
+ li $k1, '\n'
+ sw $k1, x_IO_ADDR_RANGE($15)
sw $k0, 0($15) # print CAUSE
- sw $28, 0($15)
- sw $28, 0($15)
eret # and return
nop
.end _excp_200
@@ -74,8 +97,9 @@ main: la $15, x_IO_BASE_ADDR # print out address (simulator's stdout)
##
## print sequence 2,4,6,8,cause=34, three times
##
-here: sw $5, 0($15) # print out value: 3x(2,4,6,8,34)
+here: sw $5, 0($15) # print out value: 3 times (0,2,4,6,8,34)
addiu $5, $5, 2 # value += 2
+ nop # do not cause TRAP to stall on $5
teq $5, $6 # trap if value = 10, handler does $7--
beq $7, $zero, there # if done 3 rounds, go on to next test
nop
@@ -127,4 +151,3 @@ then2: sw $7, 0($15) # print out values: (5,34,4,34,3,34,2,34,1,34)
nop
j exit
nop
-
\ No newline at end of file
diff --git a/cMIPS/tests/tlt_tlti.expected b/cMIPS/tests/tlt_tlti.expected
index f7f8131..e7de610 100644
--- a/cMIPS/tests/tlt_tlti.expected
+++ b/cMIPS/tests/tlt_tlti.expected
@@ -1,40 +1,36 @@
00000000
-08800034
+34
00000002
-08800034
+34
00000004
-08800034
+34
00000006
-08800034
+34
+
00000000
-00000000
-00000000
-08800034
+34
00000002
-08800034
+34
00000004
-08800034
+34
00000006
-08800034
-00000000
+34
00000000
-00000000
-0000000a
-08800034
-00000008
-08800034
+
00000006
-08800034
+34
00000004
-08800034
-00000000
-00000000
+34
+00000002
+34
+00000001
+
0000000a
-08800034
+34
00000008
-08800034
+34
00000006
-08800034
+34
00000004
-08800034
+34
00000000
diff --git a/cMIPS/tests/tlt_tlti.s b/cMIPS/tests/tlt_tlti.s
index bb50ef9..8dc25dd 100644
--- a/cMIPS/tests/tlt_tlti.s
+++ b/cMIPS/tests/tlt_tlti.s
@@ -5,98 +5,166 @@
.include "cMIPS.s"
.text
.align 2
+ .set noreorder # assembler should not reorder instructions
+
.global _start
.global _exit
.global exit
- .ent _start
+ .global _excp_180
+ .global excp_180
+ .global _excp_200
+ .global excp_200
##
## reset leaves processor in kernel mode, all else disabled
##
+ .ent _start
_start: nop
li $sp,(x_DATA_BASE_ADDR+x_DATA_MEM_SZ-8) # initialize SP: ramTop-8
- la $k0, main
- mtc0 $k0, cop0_EPC
- eret # go into user mode, all else disabled
- nop
+
+ la $k0, cop0_STATUS_reset # go into user mode
+ addi $k0, $k0, -2
+ addi $k0, $k0, 0b10000
+ mtc0 $k0, cop0_STATUS
+
+ j main
+ nop
exit:
-_exit: nop # flush pipeline
+_exit: nop # flush pipeline
nop
nop
nop
nop
- wait 0x3ff # and then stop VHDL simulation
+ wait # and then stop VHDL simulation
nop
nop
.end _start
+
+ ##
+ ## print CAUSE, decrement iteration control
+ ##
.org x_EXCEPTION_0180,0 # exception vector_180 at 0x00000060
- .global _excp_180
- .global excp_180
- .global _excp_200
- .global excp_200
.ent _excp_180
-excp_180:
_excp_180:
-excp_200:
-_excp_200:
mfc0 $k0, cop0_CAUSE
- sw $k0,0($15) # print CAUSE to stdout
- addiu $7,$7,-1 # and decrement $7
+ andi $k1, $k0, 0x0030
+ srl $k1, $k1, 4
+ addi $k1, $k1, '0'
+ sw $k1, x_IO_ADDR_RANGE($15)
+ andi $k1, $k0, 0x000f # keep only exception code
+ addi $k1, $k1, '0'
+ sw $k1, x_IO_ADDR_RANGE($15) # print CAUSE.exCode
+ li $k1, '\n'
+ sw $k1, x_IO_ADDR_RANGE($15)
+ addiu $7, $7, -1 # decrement iteration control
+
+ mfc0 $k1, cop0_EPC # move EPC forward to next instruction
+ addi $k1, $k1, 4
+ mtc0 $k1, cop0_EPC
+ mfc0 $k0, cop0_STATUS # go back into user mode
+ ori $k0, $k0, 0x0010
+ mtc0 $k0, cop0_STATUS
excp_180ret:
- eret
- .end _excp_180
-
-# .org (end_excp_180 + 0x20),0
-# .ent _excp_200
-#excp_200:
-#_excp_200:
-# eret
-# nop
-# .end _excp_200
-
- .org x_ENTRY_POINT,0 # normal code starts at 0x0000.0100
-main: la $15,x_IO_BASE_ADDR
- li $7,4
- li $6,10
- li $5,0
-here: sw $5, 0($15)
- addiu $5,$5,2
- tlt $5,$6
+ eret
+ .end _excp_180
+
+
+ ##
+ ## this exception should not happen
+ ##
+ .org x_EXCEPTION_0200,0
+ .ent _excp_200
+_excp_200:
+ li $28,-1
+ sw $28, 0($15) # signal exception to std_out
+ mfc0 $k0, cop0_CAUSE
+ li $k1, 'e'
+ sw $k1, x_IO_ADDR_RANGE($15)
+ li $k1, 'r'
+ sw $k1, x_IO_ADDR_RANGE($15)
+ li $k1, 'r'
+ sw $k1, x_IO_ADDR_RANGE($15)
+ li $k1, '\n'
+ sw $k1, x_IO_ADDR_RANGE($15)
+ sw $k0, 0($15) # print CAUSE
+ eret # and return
+ nop
+ .end _excp_200
+
+
+
+
+ .org x_ENTRY_POINT,0 # normal code start
+main: la $15, x_IO_BASE_ADDR # simulator's stdout
+ li $7, 4 # do loop 4 times
+ li $6, 10 # limit = 10
+ li $5, 0 # value to print
+
+ ##
+ ## print sequence 0,34, 2,34, 4,34, 6,cause=34
+ ##
+here: sw $5, 0($15)
+ addiu $5, $5, 2
+ nop # so trap will not stall on $5
+ tlt $5, $6
beq $7,$zero, there
- b here
-
-there: sw $zero, 0($15)
- sw $zero, 0($15)
- li $5,0
- li $7,4
-then: sw $5, 0($15)
- addiu $5,$5,2
- tlti $5,10
- bnez $7,then
nop
- sw $7, 0($15)
+ b here
+ nop
+
+ ## print out '\n' to separate tests
+there: li $28, '\n'
+ sw $28, x_IO_ADDR_RANGE($15)
+
+ ##
+ ## print sequence 2,34, 4,34, 6,34, 8,cause=34, 0
+ ##
+ li $5, 0
+ li $7, 4
+then: sw $5, 0($15)
+ addiu $5, $5, 2
+ tlti $5, 10
+ bnez $7, then
+ nop
+ sw $7, 0($15)
- sw $zero, 0($15)
- sw $zero, 0($15)
- li $5,1
- li $7,4
- li $6,10
+ ## print out '\n' to separate tests
+ li $28, '\n'
+ sw $28, x_IO_ADDR_RANGE($15)
+
+ ##
+ ## print sequence 6,34, 4,34, 2,34, 1
+ ##
+ li $5, 1
+ li $7, 4
+ li $6, 6
here2: sw $6, 0($15)
- tge $6,$5
- addiu $6,$6,-2
- beq $7,$zero, there2
- b here2
-
-there2: sw $zero, 0($15)
- sw $zero, 0($15)
- li $6,10
- li $7,4
-then2: sw $6, 0($15)
- tgei $6,1
- addiu $6,$6,-2
- bnez $7,then2
+ tge $6, $5
+ addiu $6, $6, -2
+ beq $6, $zero, there2
nop
- sw $7, 0($15)
- j exit
+ b here2
+ nop
+
+there2: sw $7, 0($15) # trapped 3 times: 4-3=1
+ ## print out '\n' to separate tests
+ li $28, '\n'
+ sw $28, x_IO_ADDR_RANGE($15)
+
+ ##
+ ## print sequence a,34, 8,34, 6,34, 4,cause=34
+ ##
+ li $6, 10
+ li $7, 4
+then2: sw $6, 0($15)
+ nop
+ tgei $6, 1
+ addiu $6, $6, -2
+ bnez $7, then2
+ nop
+
+ sw $7, 0($15)
+ j exit
+ nop
diff --git a/cMIPS/tests/tltu_tgeu.expected b/cMIPS/tests/tltu_tgeu.expected
index 3dca4c4..200a1b4 100644
--- a/cMIPS/tests/tltu_tgeu.expected
+++ b/cMIPS/tests/tltu_tgeu.expected
@@ -5,16 +5,16 @@
00000004
-08800034
+34
00000003
-08800034
+34
00000002
-08800034
+34
00000001
-08800034
+34
00000000
00000000
diff --git a/cMIPS/tests/tltu_tgeu.s b/cMIPS/tests/tltu_tgeu.s
index 3fbde78..88f6031 100644
--- a/cMIPS/tests/tltu_tgeu.s
+++ b/cMIPS/tests/tltu_tgeu.s
@@ -16,12 +16,13 @@
##
_start: nop
li $sp,(x_DATA_BASE_ADDR+x_DATA_MEM_SZ-8) # initialize SP: ramTop-8
- la $k0, main
- mtc0 $k0, cop0_EPC
- nop
- nop
- nop
- eret # go into user mode, all else disabled
+
+ la $k0, cop0_STATUS_reset # go into user mode
+ addi $k0, $k0, -2
+ addi $k0, $k0, 0b10000
+ mtc0 $k0, cop0_STATUS
+
+ j main
nop
exit:
@@ -37,15 +38,32 @@ _exit: nop # flush pipeline
.org x_EXCEPTION_0180,0 # exception vector_180
.ent _excp_180
-excp_180:
+ ##
+ ## print CAUSE, reset counter, decrement iteration control
+ ##
_excp_180:
mfc0 $k0, cop0_CAUSE
- addiu $7,$7,-1 # decrement iteration control
- sw $k0,0($15) # print CAUSE
- #li $k0, 0x18000000 # disable interrupts
- #mtc0 $k0, cop0_STATUS
- eret
- .end _excp_180
+ andi $k1, $k0, 0x0030
+ srl $k1, $k1, 4
+ addi $k1, $k1, '0'
+ sw $k1, x_IO_ADDR_RANGE($15)
+ andi $k1, $k0, 0x000f # keep only exception code
+ addi $k1, $k1, '0'
+ sw $k1, x_IO_ADDR_RANGE($15) # print CAUSE.exCode
+ li $k1, '\n'
+ sw $k1, x_IO_ADDR_RANGE($15)
+ li $5, 0
+ addiu $7, $7, -1 # decrement iteration control
+
+ mfc0 $k1, cop0_EPC # move EPC forward to next instruction
+ addi $k1, $k1, 4
+ mtc0 $k1, cop0_EPC
+ mfc0 $k0, cop0_STATUS # go back into user mode
+ ori $k0, $k0, 0x0010
+ mtc0 $k0, cop0_STATUS
+excp_180ret:
+ eret
+ .end _excp_180
.org x_EXCEPTION_0200,0 # exception vector_200
@@ -55,19 +73,23 @@ _excp_200:
##
## this exception should not happen
##
- li $28,'\n'
- sw $28, x_IO_ADDR_RANGE($15) # signal exception to std_out
- sw $28, x_IO_ADDR_RANGE($15) # print two \n
- mfc0 $k0, cop0_CAUSE
- sw $k0,0($15) # print CAUSE
- sw $28, x_IO_ADDR_RANGE($15)
- sw $28, x_IO_ADDR_RANGE($15)
- eret # and return
+ mfc0 $k0, cop0_CAUSE # signal exception to std_out
+ li $k1, 'e'
+ sw $k1, x_IO_ADDR_RANGE($15)
+ li $k1, 'r'
+ sw $k1, x_IO_ADDR_RANGE($15)
+ li $k1, 'r'
+ sw $k1, x_IO_ADDR_RANGE($15)
+ li $k1, '\n'
+ sw $k1, x_IO_ADDR_RANGE($15)
+ sw $k0, 0($15) # print CAUSE
+ eret # and return
.end _excp_200
- .org x_ENTRY_POINT,0 # normal code
-main: la $15,x_IO_BASE_ADDR
+
+ .org x_ENTRY_POINT,0 # normal code
+main: la $15,x_IO_BASE_ADDR # simulator's stdout
la $18, 0x80000000 # signed largest negative
la $19, 0x80000001 # signed largest negative but one
diff --git a/cMIPS/vhdl/core.vhd b/cMIPS/vhdl/core.vhd
index 3113e47..750ebf0 100644
--- a/cMIPS/vhdl/core.vhd
+++ b/cMIPS/vhdl/core.vhd
@@ -85,10 +85,8 @@ architecture rtl of core is
EX_interrupt: out std_logic;
RF_int_req: in std_logic_vector;
EX_int_req: out std_logic_vector;
- RF_tr_is_equal: in std_logic;
- EX_tr_is_equal: out std_logic;
- RF_tr_less_than: in std_logic;
- EX_tr_less_than: out std_logic);
+ RF_trap_taken: in boolean;
+ EX_trapped: out boolean);
end component reg_excp_RF_EX;
component reg_excp_EX_MM is
@@ -109,8 +107,8 @@ architecture rtl of core is
MM_cop0_a_c: out std_logic_vector;
EX_cop0_val: in std_logic_vector;
MM_cop0_val: out std_logic_vector;
- EX_trapped: in std_logic;
- MM_ex_trapped: out std_logic;
+ EX_ovfl: in boolean;
+ MM_ex_ovfl: out boolean;
EX_mfc0: in std_logic;
MM_mfc0: out std_logic);
end component reg_excp_EX_MM;
@@ -138,22 +136,23 @@ architecture rtl of core is
signal i_addr_error : std_logic;
signal interrupt,EX_interrupt, exception_stall : std_logic;
- signal exception_taken, interrupt_taken, trap_taken : std_logic;
+ signal exception_taken, interrupt_taken : std_logic;
signal nullify, nullify_EX, abort : std_logic;
- signal addrError, MM_abort, WB_abort : boolean;
+ signal addrError, MM_abort, WB_abort: boolean;
signal PC_abort, RF_PC_abort, EX_PC_abort : boolean;
signal IF_excp_type,RF_excp_type,EX_excp_type,WB_excp_type: exception_type := exNOP;
signal MM_excp_type, MM_excp_type_i, TLB_excp_type : exception_type;
signal trap_instr,EX_trap_instr: instr_type;
signal RF_PC,EX_PC,MM_PC,WB_PC, LLaddr: reg32;
signal EX_LLbit,MM_LLbit,WB_LLbit: std_logic;
- signal LL_update,LL_SC_abort,LL_SC_differ,EX_trapped,MM_ex_trapped: std_logic;
+ signal LL_update,LL_SC_abort,LL_SC_differ: std_logic;
+ signal EX_trapped, EX_ovfl,MM_ex_ovfl, trap_taken: boolean;
signal int_req, EX_int_req: reg8;
signal RF_nmi,EX_nmi : std_logic;
signal EX_mfc0, MM_mfc0 : std_logic;
signal can_trap,EX_can_trap,MM_can_trap,WB_can_trap: reg2;
signal is_trap, tr_signed, tr_stall: std_logic;
- signal tr_is_equal,EX_tr_is_equal, tr_less_than,EX_tr_less_than: std_logic;
+ signal tr_is_equal, tr_less_than: std_logic;
signal tr_fwd_A, tr_fwd_B, tr_result : reg32;
signal excp_IF_RF_ld,excp_RF_EX_ld,excp_EX_MM_ld,excp_MM_WB_ld: std_logic;
signal update, not_stalled: std_logic;
@@ -165,7 +164,7 @@ architecture rtl of core is
signal count_eq_compare,count_update,count_enable : std_logic;
signal exception,EX_exception,is_exception : exception_type := exNOP;
signal ExcCode : reg5 := cop0code_NULL;
- signal exception_num,exception_dec,TLB_excp_num : integer; -- for debugging only
+ signal exception_num,exception_dec,TLB_excp_num,trap_dec: integer; -- debugging
signal RF_is_delayslot,EX_is_delayslot,MM_is_delayslot,WB_is_delayslot,is_delayslot : std_logic;
signal cop0_sel, EX_cop0_sel, epc_source : reg3;
signal cop0_reg,EX_cop0_reg : reg5;
@@ -599,13 +598,13 @@ architecture rtl of core is
(NIL, '1','0',opNOP, "001",'0','0','0',"00","00"), --45
(NIL, '1','0',opNOP, "001",'0','0','0',"00","00"), --46
(NIL, '1','0',opNOP, "001",'0','0','0',"00","00"), --47
- (TGE, '1','0',trGEQ, "001",'1','0','0',"00","01"), --tge=48
- (TGEU, '1','0',trGEU, "001",'1','0','0',"00","01"), --tgeu=49
- (TLT, '1','0',trLTH, "001",'1','0','0',"00","01"), --tlt=50
- (TLTU, '1','0',trLTU, "001",'1','0','0',"00","01"), --tltu=51
- (TEQ, '1','0',trEQU, "001",'1','0','0',"00","01"), --teq=52
+ (TGE, '1','0',trGEQ, "001",'1','0','0',"00","10"), --tge=48
+ (TGEU, '1','0',trGEU, "001",'1','0','0',"00","10"), --tgeu=49
+ (TLT, '1','0',trLTH, "001",'1','0','0',"00","10"), --tlt=50
+ (TLTU, '1','0',trLTU, "001",'1','0','0',"00","10"), --tltu=51
+ (TEQ, '1','0',trEQU, "001",'1','0','0',"00","10"), --teq=52
(NIL, '1','0',opNOP, "001",'0','0','0',"00","00"), --53
- (TNE, '1','0',trNEQ, "001",'1','0','0',"00","01"), --tne=54
+ (TNE, '1','0',trNEQ, "001",'1','0','0',"00","10"), --tne=54
(NIL, '1','0',opNOP, "001",'0','0','0',"00","00"), --55
(NIL, '1','0',opNOP, "001",'0','0','0',"00","00"), --56
(NIL, '1','0',opNOP, "001",'0','0','0',"00","00"), --57
@@ -1080,7 +1079,7 @@ begin
if RF_instruction = x"000000c0" then
i_exception := exEHB;
end if;
- when others => i_exception := exTRAP;
+ when others => i_exception := exNOP;
end case;
end if;
@@ -1094,7 +1093,7 @@ begin
i_oper := opNOP; -- no ALU operation
if (rimm_word.trap = '1') then -- traps
- i_exception := exTRAP;
+ i_exception := exNOP;
end if;
when b"010000" => -- COP-0
@@ -1606,18 +1605,7 @@ begin
interrupt <= int_req(7) or int_req(6) or int_req(5) or int_req(4) or
int_req(3) or int_req(2) or int_req(1) or int_req(0);
- tr_signed <= '0' when ((funct_word.trap = '1' and
- ((funct_word.oper = trGEU)or(funct_word.oper = trLTU)))
- or
- (rimm_word.trap = '1' and
- ((rimm_word.br_t = tGEU)or(rimm_word.br_t = tLTU))))
- else '1';
-
- tr_is_equal <= '1' when (tr_fwd_A = tr_fwd_B) else '0';
-
- U_COMP_TRAP: subtr32
- port map (tr_fwd_A, tr_fwd_B, tr_result, tr_signed, open, tr_less_than);
-
+
RF_FORWARDING_TRAPS: process (a_rs,a_rt,rimm_word,displ32,
EX_wreg,EX_a_c,MM_wreg,MM_a_c,
@@ -1662,7 +1650,39 @@ begin
end if;
end process RF_FORWARDING_TRAPS;
+ tr_signed <= '0' when ((funct_word.trap = '1' and
+ ((funct_word.oper = trGEU)or(funct_word.oper = trLTU)))
+ or
+ (rimm_word.trap = '1' and
+ ((rimm_word.br_t = tGEU)or(rimm_word.br_t = tLTU))))
+ else '1';
+
+ tr_is_equal <= '1' when (tr_fwd_A = tr_fwd_B) else '0';
+
+ U_COMP_TRAP: subtr32
+ port map (tr_fwd_A, tr_fwd_B, tr_result, tr_signed, open, tr_less_than);
+
+ trap_dec <= instr_type'pos(trap_instr); -- debugging only
+
+ RF_EVALUATE_TRAPS: process (trap_instr, tr_is_equal, tr_less_than)
+ variable i_take_trap : boolean;
+ begin
+ case trap_instr is
+ when TEQ | TEQI =>
+ i_take_trap := tr_is_equal = '1';
+ when TNE | TNEI =>
+ i_take_trap := tr_is_equal = '0';
+ when TLT | TLTI | TLTU | TLTIU =>
+ i_take_trap := tr_less_than = '1';
+ when TGE | TGEI | TGEU | TGEIU =>
+ i_take_trap := tr_less_than = '0';
+ when others =>
+ i_take_trap := FALSE;
+ end case;
+ trap_taken <= i_take_trap;
+ end process RF_EVALUATE_TRAPS;
+
-- ----------------------------------------------------------------------
PIPESTAGE_EXCP_RF_EX: reg_excp_RF_EX
port map (clk, rst, excp_RF_EX_ld, can_trap,EX_can_trap,
@@ -1671,20 +1691,21 @@ begin
RF_is_delayslot,EX_is_delayslot,
RF_PC_abort,EX_PC_abort, RF_PC,EX_PC, RF_nmi,EX_nmi,
interrupt,EX_interrupt, int_req,EX_int_req,
- tr_is_equal,EX_tr_is_equal, tr_less_than,EX_tr_less_than);
+ trap_taken,EX_trapped);
-- EX execute exception ---------------------------------------------
-
+
-- check for overflow in EX, send it to MM for later processing
- ex_trapped <= '1' when (EX_can_trap = b"10" and ovfl = '1') else '0';
+ EX_ovfl <= (EX_can_trap = b"10" and ovfl = '1');
- is_exception <= TLB_excp_type when tlb_exception else
- MM_excp_type when addrError else
- exOvfl when MM_ex_trapped = '1' else
- IFaddressError when EX_PC_abort else
+ is_exception <= TLB_excp_type when tlb_exception else
+ MM_excp_type when addrError else
+ exTrap when Ex_trapped else
+ exOvfl when MM_ex_ovfl else
+ IFaddressError when EX_PC_abort else
EX_exception;
exception_num <= exception_type'pos(is_exception); -- for debugging only
@@ -1692,16 +1713,15 @@ begin
-- STATUS -- pg 79 -- cop0_12 --------------------
COP0_DECODE_EXCEPTION_AND_UPDATE_STATUS:
- process (EX_a_rt, is_exception, EX_trap_instr,
+ process (EX_a_rt, is_exception, cop0_inp,
EX_cop0_reg, EX_cop0_sel, EX_nmi, EX_interrupt,EX_int_req,
RF_is_delayslot, EX_is_delayslot, MM_is_delayslot, WB_is_delayslot,
- cop0_inp, EX_tr_is_equal, EX_tr_less_than,
INDEX, RANDOM, EntryLo0, EntryLo1, CONTEXT, PAGEMASK, WIRED,
EntryHi, COUNT, COMPARE, STATUS, CAUSE, EPC, BadVAddr,
rom_stall,ram_stall)
variable newSTATUS, i_COP0_rd : reg32;
- variable i_update,i_epc_update,i_stall,i_nullify,i_take_trap : std_logic;
+ variable i_update,i_epc_update,i_stall,i_nullify : std_logic;
variable i_a_c,i_update_r : reg5;
variable i_epc_source : reg3;
@@ -1716,12 +1736,11 @@ begin
i_COP0_rd := x"00000000";
i_stall := '0';
i_nullify := '0';
- i_take_trap := '0';
+
nullify_EX <= '0';
exception_taken <= '0'; -- for debugging only
interrupt_taken <= '0';
- trap_taken <= '0';
ExcCode <= cop0code_NULL;
EX_mfc0 <= '0';
is_delayslot <= '0';
@@ -1802,7 +1821,7 @@ begin
i_stall := '0';
EX_mfc0 <= '1';
- when exERET => -- exception return
+ when exERET => -- EXCEPTION RETURN
newSTATUS(STATUS_EXL) := '0'; -- leave exception level
i_update := '1';
i_update_r := cop0reg_STATUS;
@@ -1810,57 +1829,54 @@ begin
i_nullify := '1'; -- nullify instructions in IF,RF
- when exTRAP | exSYSCALL | exBREAK => -- trap instruction
+ when exSYSCALL | exBREAK => -- SYSCALL, BREAK
i_stall := '0';
- case EX_trap_instr is
- when TEQ | TEQI =>
- i_take_trap := EX_tr_is_equal;
- when TNE | TNEI =>
- i_take_trap := not(EX_tr_is_equal);
- when TLT | TLTI | TLTU | TLTIU =>
- i_take_trap := EX_tr_less_than;
- when TGE | TGEI | TGEU | TGEIU =>
- i_take_trap := not(EX_tr_less_than);
- when SYSCALL =>
- i_take_trap := '1';
- when BREAK =>
- i_take_trap := '1';
- when others =>
- i_take_trap := '0';
- end case;
- if i_take_trap = '1' then
- trap_taken <= '1';
- case EX_trap_instr is
- when TEQ | TEQI | TNE | TNEI | TLT | TLTI | TLTU | TLTIU |
- TGE | TGEI | TGEU | TGEIU => ExcCode <= cop0code_Tr;
- when SYSCALL => ExcCode <= cop0code_Sys;
- when BREAK => ExcCode <= cop0code_Bp;
- when others => null;
- end case;
- newSTATUS(STATUS_EXL) := '1'; -- at exception level
- newSTATUS(STATUS_UM) := '0'; -- enter kernel mode
- newSTATUS(STATUS_IE) := '0'; -- disable interrupts
- i_update := '1';
- i_update_r := cop0reg_STATUS;
- i_stall := '0';
- i_epc_update := '0';
- i_nullify := '1'; -- nullify instructions in IF,RF
- if EX_is_delayslot = '1' then -- instr is in delay slot
- i_epc_source := EPC_src_EX; -- EX_PC, re-execute branch/jump
- is_delayslot <= EX_is_delayslot;
- else
- i_epc_source := EPC_src_RF; -- RF_PC
- is_delayslot <= RF_is_delayslot;
- end if;
+ if is_exception = exSYSCALL then
+ ExcCode <= cop0code_Sys;
+ else
+ ExcCode <= cop0code_Bp;
+ end if;
+ newSTATUS(STATUS_EXL) := '1'; -- at exception level
+ newSTATUS(STATUS_UM) := '0'; -- enter kernel mode
+ newSTATUS(STATUS_IE) := '0'; -- disable interrupts
+ i_update := '1';
+ i_update_r := cop0reg_STATUS;
+ i_stall := '0'; -- do not stall
+ i_epc_update := '0';
+ i_nullify := '1'; -- nullify instructions in IF,RF
+ if EX_is_delayslot = '1' then -- instr is in delay slot
+ i_epc_source := EPC_src_EX; -- EX_PC, re-execute branch/jump
+ is_delayslot <= EX_is_delayslot;
else
- trap_taken <= '0';
+ i_epc_source := EPC_src_RF; -- RF_PC
+ is_delayslot <= RF_is_delayslot;
end if;
+
+ when exTRAP => -- TRAP detected one cycle earlier
+ ExcCode <= cop0code_Tr;
+ newSTATUS(STATUS_EXL) := '1'; -- at exception level
+ newSTATUS(STATUS_UM) := '0'; -- enter kernel mode
+ newSTATUS(STATUS_IE) := '0'; -- disable interrupts
+ i_update := '1';
+ i_update_r := cop0reg_STATUS;
+ i_stall := '0';
+ i_epc_update := '0';
+ i_nullify := '1'; -- nullify instructions in IF,RF
+ if EX_is_delayslot = '1' then -- instr is in delay slot
+ i_epc_source := EPC_src_MM; -- EX_PC, re-execute branch/jump
+ is_delayslot <= EX_is_delayslot;
+ else
+ i_epc_source := EPC_src_EX; -- RF_PC
+ is_delayslot <= RF_is_delayslot;
+ end if;
+
+
when exLL => -- load linked (not a real exception)
i_update := '1';
i_update_r := cop0reg_LLaddr;
- -- when exSC => null; if treated here, SC might delay an interrupt
+ -- when exSC => null; if treated here, SC might delay an interrupt
when exRESV_INSTR => -- reserved instruction ABORT SIMULATION
@@ -2075,7 +2091,7 @@ begin
-- Select input to PC on an exception --------------------
COP0_SEL_EPC: process (is_exception, EX_nmi, EX_interrupt, STATUS, CAUSE,
- trap_taken, rom_stall, ram_stall)
+ EX_trapped, rom_stall, ram_stall)
variable i_excp_PCsel : reg3;
begin
@@ -2092,12 +2108,12 @@ begin
| exTLBinvalIF | exTLBinvalRD | exTLBinvalWR | exTLBmod =>
i_excp_PCsel := PCsel_EXC_0180; -- PC <= exception_180
- when exTRAP =>
- if trap_taken = '1' then
- i_excp_PCsel := PCsel_EXC_0180; -- PC <= exception_180
- else
- i_excp_PCsel := PCsel_EXC_none;
- end if;
+ when exTRAP =>
+ if EX_trapped then
+ i_excp_PCsel := PCsel_EXC_0180; -- PC <= exception_180
+ else
+ i_excp_PCsel := PCsel_EXC_none;
+ end if;
when exTLBrefillIF | exTLBrefillRD | exTLBrefillWR =>
i_excp_PCsel := PCsel_EXC_0000; -- PC <= exception_0000
@@ -2119,7 +2135,7 @@ begin
end if;
else
i_excp_PCsel := PCsel_EXC_none; -- should never get here
- end if; -- NMI or else interrupt
+ end if; -- NMI or interrupt
end case;
@@ -2942,7 +2958,7 @@ begin
EX_LLbit,MM_LLbit, addrError,MM_abort,
EX_is_delayslot,MM_is_delayslot,
EX_cop0_a_c,MM_cop0_a_c, EX_cop0_val,MM_cop0_val,
- EX_trapped, MM_ex_trapped, EX_mfc0,MM_mfc0);
+ EX_ovfl, MM_ex_ovfl, EX_mfc0,MM_mfc0);
-- ----------------------------------------------------------------------
diff --git a/cMIPS/vhdl/exception.vhd b/cMIPS/vhdl/exception.vhd
index f8f3789..6cf8343 100644
--- a/cMIPS/vhdl/exception.vhd
+++ b/cMIPS/vhdl/exception.vhd
@@ -85,10 +85,8 @@ entity reg_excp_RF_EX is
EX_interrupt: out std_logic;
RF_int_req: in reg8;
EX_int_req: out reg8;
- RF_tr_is_equal: in std_logic;
- EX_tr_is_equal: out std_logic;
- RF_tr_less_than: in std_logic;
- EX_tr_less_than: out std_logic);
+ RF_trap_taken: in boolean;
+ EX_trapped: out boolean);
end reg_excp_RF_EX;
architecture funcional of reg_excp_RF_EX is
@@ -98,6 +96,7 @@ begin
if rst = '0' then
EX_can_trap <= b"00";
EX_is_delayslot <= '0';
+ EX_trapped <= FALSE;
elsif rising_edge(clk) then
if ld = '0' then
EX_can_trap <= RF_can_trap ;
@@ -111,8 +110,7 @@ begin
EX_nmi <= RF_nmi ;
EX_interrupt <= RF_interrupt ;
EX_int_req <= RF_int_req ;
- EX_tr_is_equal <= RF_tr_is_equal ;
- EX_tr_less_than <= RF_tr_less_than ;
+ EX_trapped <= RF_trap_taken ;
end if;
end if;
end process;
@@ -145,8 +143,8 @@ entity reg_excp_EX_MM is
MM_cop0_a_c: out reg5;
EX_cop0_val: in reg32;
MM_cop0_val: out reg32;
- EX_trapped: in std_logic;
- MM_ex_trapped: out std_logic;
+ EX_ovfl: in boolean;
+ MM_ex_ovfl: out boolean;
EX_mfc0: in std_logic;
MM_mfc0: out std_logic);
end reg_excp_EX_MM;
@@ -158,19 +156,19 @@ begin
if rst = '0' then
MM_can_trap <= b"00";
MM_cop0_LLbit <= '0';
- MM_ex_trapped <= '0';
+ MM_ex_ovfl <= FALSE;
elsif rising_edge(clk) then
if ld = '0' then
- MM_excp_type <= EX_excp_type ;
- MM_can_trap <= EX_can_trap ;
- MM_PC <= EX_PC ;
- MM_cop0_LLbit <= EX_cop0_LLbit ;
- MM_abort <= addrError ;
+ MM_excp_type <= EX_excp_type ;
+ MM_can_trap <= EX_can_trap ;
+ MM_PC <= EX_PC ;
+ MM_cop0_LLbit <= EX_cop0_LLbit ;
+ MM_abort <= addrError ;
MM_is_delayslot <= EX_is_delayslot;
- MM_cop0_a_c <= EX_cop0_a_c ;
- MM_cop0_val <= EX_cop0_val ;
- MM_ex_trapped <= EX_trapped ;
- MM_mfc0 <= EX_mfc0 ;
+ MM_cop0_a_c <= EX_cop0_a_c ;
+ MM_cop0_val <= EX_cop0_val ;
+ MM_ex_ovfl <= EX_ovfl ;
+ MM_mfc0 <= EX_mfc0 ;
end if;
end if;
end process;
@@ -191,8 +189,8 @@ entity reg_excp_MM_WB is
WB_can_trap: out reg2;
MM_excp_type: in exception_type;
WB_excp_type: out exception_type;
- MM_PC: in std_logic_vector;
- WB_PC: out std_logic_vector;
+ MM_PC: in reg32;
+ WB_PC: out reg32;
MM_cop0_LLbit: in std_logic;
WB_cop0_LLbit: out std_logic;
MM_abort: in boolean;
diff --git a/cMIPS/vhdl/packageMemory.vhd b/cMIPS/vhdl/packageMemory.vhd
index d8143e4..f1fc694 100644
--- a/cMIPS/vhdl/packageMemory.vhd
+++ b/cMIPS/vhdl/packageMemory.vhd
@@ -29,9 +29,9 @@ package p_MEMORY is
-- which means having an adder in the critical path. Not good.
-- The address ranges for ROM, RAM and I/O must be distinct in the
- -- uppermost 12 bits of the address (bits 31..20).
+ -- uppermost 12 bits of the address (bits 31..16).
constant HI_SEL_BITS : integer := 31;
- constant LO_SEL_BITS : integer := 20;
+ constant LO_SEL_BITS : integer := 16;
-- x_IO_ADDR_RANGE can have only ONE bit set, thus being a power of 2.
--
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