1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
|
open Netlist_gen
let zeroes n =
const (String.make n '0')
let one n =
const "1" ++ zeroes (n-1)
let two n =
const "01" ++ zeroes (n-2)
let rec rep n k =
if n = 1 then k
else
let s = rep (n/2) k in
if n mod 2 = 0 then s ++ s else s ++ s ++ k
let rec eq_c n v c = (* v is a value, c is a constant *)
if n = 1 then
if c = 1 then v else not v
else
(eq_c 1 (v ** 0) (c mod 2)) ^& (eq_c (n-1) (v % (1, n-1)) (c/2))
let rec all1 n x =
if n = 1 then
x
else
(x ** 0) ^& (all1 (n-1) (x % (1, n-1)))
let rec nonnull n a =
if n = 1 then
a
else
(a ** 0) ^| (nonnull (n-1) (a % (1, n-1)))
let rec sign_extend n_a n_dest a =
a ++ rep (n_dest - n_a) (a ** (n_a - 1))
(* Arithmetic operations *)
let fulladder a b c =
let s = a ^^ b ^^ c in
let r = (a ^& b) ^| ((a ^^ b) ^& c) in
s, r
let rec nadder_with_carry n a b c_in =
if n = 1 then fulladder a b c_in
else
let s_n, c_n1 = fulladder (a ** 0) (b ** 0) c_in in
let s_n1, c_out = nadder_with_carry (n-1) (a % (1, n-1)) (b % (1, n-1)) c_n1 in
s_n ++ s_n1, c_out
let nadder n a b =
let a, b = nadder_with_carry n a b (const "0") in
b ^. a
let rec nsubber n a b =
zeroes n (* TODO *)
let rec nmul n a b start_signal =
zeroes n, zeroes n, start_signal (* TODO : retuns lo and hi part of 32-bit answer *)
let rec ndiv n a b start_signal =
zeroes n, zeroes n, start_signal (* TODO : returns quotient and remainder *)
let rec nmulu n a b start_signal =
zeroes n, zeroes n, start_signal (* TODO : same as nmul but unsigned *)
let rec ndivu n a b start_signal =
zeroes n, zeroes n, start_signal (* TODO : save as ndiv but unsigned *)
(* Shifts *)
let npshift_signed n p a b =
a (* TODO (here b is a signed integer on p bits) *)
let op_lsl n a b =
a (* TODO (b is unsigned, same size n) *)
let op_lsr n a b =
a (* TODO (b is unsigned, same size n) *)
let op_asr n a b =
a (* TODO (b unsigned size n) *)
(* Comparisons *)
let rec eq_n n a b =
all1 n (not (a ^^ b))
let rec ne_n n a b =
nonnull n (a ^^ b)
let rec lt_n n a b =
const "0" (* TODO : less than *)
let rec ult_n n a b =
const "0" (* TODO : less than, unsigned *)
let rec le_n n a b =
const "0" (* TODO : less than or equal *)
let rec ule_n n a b =
const "0" (* TODO : less than or equal, unsigned *)
(* Big pieces *)
let alu_comparer n f0 f a b =
(*
f0 f action
-- - ------
0 0 equal
0 1 not equal
0 2 equal
0 3 not equal
1 0 lt
1 1 le
1 2 lt unsigned
1 3 le unsigned
*)
let eq_ne = mux (f ** 0) (eq_n n a b) (ne_n n a b) in
let lte_signed = mux (f ** 0) (lt_n n a b) (le_n n a b) in
let lte_unsigned = mux (f ** 0) (ult_n n a b) (ule_n n a b) in
let lte = mux (f ** 1) lte_signed lte_unsigned in
mux f0 eq_ne lte
let alu_arith f1 f a b start_signal =
(* See table for ALU below *)
let add = nadder 16 a b in
let sub = nsubber 16 a b in
let mul, mul2, mul_end_signal = nmul 16 a b start_signal in
let div, div2, div_end_signal = ndiv 16 a b start_signal in
let mulu, mulu2, mulu_end_signal = nmulu 16 a b start_signal in
let divu, divu2, divu_end_signal = ndivu 16 a b start_signal in
let q00 = mux (f ** 0) add sub in
let q01 = mux (f ** 0) mul div in
let q03 = mux (f ** 0) mulu divu in
let q10 = mux (f ** 1) q00 q01 in
let q11 = mux (f ** 1) q00 q03 in
let q = mux f1 q10 q11 in
let r01 = mux (f ** 0) mul2 div2 in
let r03 = mux (f ** 0) mulu2 divu2 in
let r10 = mux (f ** 1) (zeroes 16) r01 in
let r11 = mux (f ** 1) (zeroes 16) r03 in
let r = mux f1 r10 r11 in
let s01 = mux (f ** 0) mul_end_signal div_end_signal in
let s03 = mux (f ** 0) mulu_end_signal divu_end_signal in
let s10 = mux (f ** 1) start_signal s01 in
let s11 = mux (f ** 1) start_signal s03 in
let end_signal = mux f1 s10 s11 in
q, r, end_signal
let alu_logic f a b =
(* See table for ALU below *)
let q0 = mux (f ** 0) (a ^| b) (a ^& b) in
let q1 = mux (f ** 0) (a ^^ b) (not (a ^| b)) in
mux (f ** 1) q0 q1
let alu_shifts f a b =
(* See table for ALU below *)
let q1 = mux (f ** 0) (op_lsr 16 a b) (op_asr 16 a b) in
mux (f ** 1) (op_lsl 16 a b) q1
let alu f1 f0 f a b start_signal =
(*
f0 f1 f action
-- -- - ------
0 0 0 add
0 0 1 sub
0 0 2 mul
0 0 3 div
0 1 0 addu
0 1 1 subu
0 1 2 mulu
0 1 3 divu
1 0 0 or
1 0 1 and
1 0 2 xor
1 0 3 nor
1 1 0 lsl
1 1 1 lsl
1 1 2 lsr
1 1 3 asr
*)
let arith, arith_r, arith_end_signal = alu_arith f1 f a b start_signal in
let logic = alu_logic f a b in
let shifts = alu_shifts f a b in
let q0 = mux f1 logic shifts in
let s = mux f0 arith q0 in
let r = mux f0 arith_r (zeroes 16) in
let end_signal = mux f0 arith_end_signal start_signal in
s, r, end_signal
|
