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jservjserv
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Merge pull request #103 from sysprog21/show-entropy
Provide an option to show/hide Shannon entropy
2 parents a68ceaa + f7cffcb commit c8886c6

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7 files changed

+332
-1
lines changed

7 files changed

+332
-1
lines changed

‎Makefile

+1
Original file line numberDiff line numberDiff line change
@@ -39,6 +39,7 @@ $(GIT_HOOKS):
3939

4040
OBJS := qtest.o report.o console.o harness.o queue.o \
4141
random.o dudect/constant.o dudect/fixture.o dudect/ttest.o \
42+
shannon_entropy.o \
4243
linenoise.o web.o
4344

4445
deps := $(OBJS:%.o=.%.o.d)

‎console.c

+2
Original file line numberDiff line numberDiff line change
@@ -17,6 +17,7 @@
1717

1818
/* Some global values */
1919
int simulation = 0;
20+
int show_entropy = 0;
2021
static cmd_element_t *cmd_list = NULL;
2122
static param_element_t *param_list = NULL;
2223
static bool block_flag = false;
@@ -435,6 +436,7 @@ void init_cmd()
435436
add_param("verbose", &verblevel, "Verbosity level", NULL);
436437
add_param("error", &err_limit, "Number of errors until exit", NULL);
437438
add_param("echo", &echo, "Do/don't echo commands", NULL);
439+
add_param("entropy", &show_entropy, "Show/Hide Shannon entropy", NULL);
438440

439441
init_in();
440442
init_time(&last_time);

‎log2_lshift16.h

+282
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,282 @@
1+
/*
2+
* Generate precalculated values of log2 with assumption that arg will be left
3+
* shifted by 16 bit and return value of log2_lshift16() will be left shifted
4+
* by 3 bit All that shifts used for avoid of using floating point in
5+
* calculation.
6+
*/
7+
8+
#include <stdint.h>
9+
10+
#define LOG2_ARG_SHIFT (1 << 16)
11+
#define LOG2_RET_SHIFT (1 << 3)
12+
13+
/* store precalculated function (log2(arg << 24)) << 3 */
14+
static inline int log2_lshift16(uint64_t lshift16)
15+
{
16+
if (lshift16 < 558) {
17+
if (lshift16 < 54) {
18+
if (lshift16 < 13) {
19+
if (lshift16 < 7) {
20+
if (lshift16 < 1)
21+
return -136;
22+
if (lshift16 < 2)
23+
return -123;
24+
if (lshift16 < 3)
25+
return -117;
26+
if (lshift16 < 4)
27+
return -113;
28+
if (lshift16 < 5)
29+
return -110;
30+
if (lshift16 < 6)
31+
return -108;
32+
if (lshift16 < 7)
33+
return -106;
34+
} else {
35+
if (lshift16 < 8)
36+
return -104;
37+
if (lshift16 < 9)
38+
return -103;
39+
if (lshift16 < 10)
40+
return -102;
41+
if (lshift16 < 11)
42+
return -100;
43+
if (lshift16 < 12)
44+
return -99;
45+
if (lshift16 < 13)
46+
return -98;
47+
}
48+
} else {
49+
if (lshift16 < 29) {
50+
if (lshift16 < 15)
51+
return -97;
52+
if (lshift16 < 16)
53+
return -96;
54+
if (lshift16 < 17)
55+
return -95;
56+
if (lshift16 < 19)
57+
return -94;
58+
if (lshift16 < 21)
59+
return -93;
60+
if (lshift16 < 23)
61+
return -92;
62+
if (lshift16 < 25)
63+
return -91;
64+
if (lshift16 < 27)
65+
return -90;
66+
if (lshift16 < 29)
67+
return -89;
68+
} else {
69+
if (lshift16 < 32)
70+
return -88;
71+
if (lshift16 < 35)
72+
return -87;
73+
if (lshift16 < 38)
74+
return -86;
75+
if (lshift16 < 41)
76+
return -85;
77+
if (lshift16 < 45)
78+
return -84;
79+
if (lshift16 < 49)
80+
return -83;
81+
if (lshift16 < 54)
82+
return -82;
83+
}
84+
}
85+
} else {
86+
if (lshift16 < 181) {
87+
if (lshift16 < 99) {
88+
if (lshift16 < 59)
89+
return -81;
90+
if (lshift16 < 64)
91+
return -80;
92+
if (lshift16 < 70)
93+
return -79;
94+
if (lshift16 < 76)
95+
return -78;
96+
if (lshift16 < 83)
97+
return -77;
98+
if (lshift16 < 91)
99+
return -76;
100+
if (lshift16 < 99)
101+
return -75;
102+
} else {
103+
if (lshift16 < 108)
104+
return -74;
105+
if (lshift16 < 117)
106+
return -73;
107+
if (lshift16 < 128)
108+
return -72;
109+
if (lshift16 < 140)
110+
return -71;
111+
if (lshift16 < 152)
112+
return -70;
113+
if (lshift16 < 166)
114+
return -69;
115+
if (lshift16 < 181)
116+
return -68;
117+
}
118+
} else {
119+
if (lshift16 < 304) {
120+
if (lshift16 < 197)
121+
return -67;
122+
if (lshift16 < 215)
123+
return -66;
124+
if (lshift16 < 235)
125+
return -65;
126+
if (lshift16 < 256)
127+
return -64;
128+
if (lshift16 < 279)
129+
return -63;
130+
if (lshift16 < 304)
131+
return -62;
132+
} else {
133+
if (lshift16 < 332)
134+
return -61;
135+
if (lshift16 < 362)
136+
return -60;
137+
if (lshift16 < 395)
138+
return -59;
139+
if (lshift16 < 431)
140+
return -58;
141+
if (lshift16 < 470)
142+
return -57;
143+
if (lshift16 < 512)
144+
return -56;
145+
if (lshift16 < 558)
146+
return -55;
147+
}
148+
}
149+
}
150+
} else {
151+
if (lshift16 < 6317) {
152+
if (lshift16 < 2048) {
153+
if (lshift16 < 1117) {
154+
if (lshift16 < 609)
155+
return -54;
156+
if (lshift16 < 664)
157+
return -53;
158+
if (lshift16 < 724)
159+
return -52;
160+
if (lshift16 < 790)
161+
return -51;
162+
if (lshift16 < 861)
163+
return -50;
164+
if (lshift16 < 939)
165+
return -49;
166+
if (lshift16 < 1024)
167+
return -48;
168+
if (lshift16 < 1117)
169+
return -47;
170+
} else {
171+
if (lshift16 < 1218)
172+
return -46;
173+
if (lshift16 < 1328)
174+
return -45;
175+
if (lshift16 < 1448)
176+
return -44;
177+
if (lshift16 < 1579)
178+
return -43;
179+
if (lshift16 < 1722)
180+
return -42;
181+
if (lshift16 < 1878)
182+
return -41;
183+
if (lshift16 < 2048)
184+
return -40;
185+
}
186+
} else {
187+
if (lshift16 < 3756) {
188+
if (lshift16 < 2233)
189+
return -39;
190+
if (lshift16 < 2435)
191+
return -38;
192+
if (lshift16 < 2656)
193+
return -37;
194+
if (lshift16 < 2896)
195+
return -36;
196+
if (lshift16 < 3158)
197+
return -35;
198+
if (lshift16 < 3444)
199+
return -34;
200+
if (lshift16 < 3756)
201+
return -33;
202+
} else {
203+
if (lshift16 < 4096)
204+
return -32;
205+
if (lshift16 < 4467)
206+
return -31;
207+
if (lshift16 < 4871)
208+
return -30;
209+
if (lshift16 < 5312)
210+
return -29;
211+
if (lshift16 < 5793)
212+
return -28;
213+
if (lshift16 < 6317)
214+
return -27;
215+
}
216+
}
217+
} else {
218+
if (lshift16 < 21247) {
219+
if (lshift16 < 11585) {
220+
if (lshift16 < 6889)
221+
return -26;
222+
if (lshift16 < 7512)
223+
return -25;
224+
if (lshift16 < 8192)
225+
return -24;
226+
if (lshift16 < 8933)
227+
return -23;
228+
if (lshift16 < 9742)
229+
return -22;
230+
if (lshift16 < 10624)
231+
return -21;
232+
if (lshift16 < 11585)
233+
return -20;
234+
} else {
235+
if (lshift16 < 12634)
236+
return -19;
237+
if (lshift16 < 13777)
238+
return -18;
239+
if (lshift16 < 15024)
240+
return -17;
241+
if (lshift16 < 16384)
242+
return -16;
243+
if (lshift16 < 17867)
244+
return -15;
245+
if (lshift16 < 19484)
246+
return -14;
247+
if (lshift16 < 21247)
248+
return -13;
249+
}
250+
} else {
251+
if (lshift16 < 35734) {
252+
if (lshift16 < 23170)
253+
return -12;
254+
if (lshift16 < 25268)
255+
return -11;
256+
if (lshift16 < 27554)
257+
return -10;
258+
if (lshift16 < 30048)
259+
return -9;
260+
if (lshift16 < 32768)
261+
return -8;
262+
if (lshift16 < 35734)
263+
return -7;
264+
} else {
265+
if (lshift16 < 38968)
266+
return -6;
267+
if (lshift16 < 42495)
268+
return -5;
269+
if (lshift16 < 46341)
270+
return -4;
271+
if (lshift16 < 50535)
272+
return -3;
273+
if (lshift16 < 55109)
274+
return -2;
275+
if (lshift16 < 60097)
276+
return -1;
277+
}
278+
}
279+
}
280+
}
281+
return 0;
282+
}

‎qtest.c

+11-1
Original file line numberDiff line numberDiff line change
@@ -17,6 +17,10 @@
1717
#include "dudect/fixture.h"
1818
#include "list.h"
1919

20+
/* Shannon entropy */
21+
extern double shannon_entropy(const uint8_t *input_data);
22+
extern int show_entropy;
23+
2024
/* Our program needs to use regular malloc/free */
2125
#define INTERNAL 1
2226
#include "harness.h"
@@ -803,8 +807,14 @@ static bool show_queue(int vlevel)
803807
if (exception_setup(true)) {
804808
while (ok && ori != cur && cnt < lcnt) {
805809
element_t *e = list_entry(cur, element_t, list);
806-
if (cnt < big_list_size)
810+
if (cnt < big_list_size) {
807811
report_noreturn(vlevel, cnt == 0 ? "%s" : " %s", e->value);
812+
if (show_entropy) {
813+
report_noreturn(
814+
vlevel, "(%3.2f%%)",
815+
shannon_entropy((const uint8_t *) e->value));
816+
}
817+
}
808818
cnt++;
809819
cur = cur->next;
810820
ok = ok && !error_check();

‎scripts/aspell-pws

+1
Original file line numberDiff line numberDiff line change
@@ -289,3 +289,4 @@ alloc
289289
adjtime
290290
perf
291291
uring
292+
Shannon

‎scripts/pre-commit.hook

+1
Original file line numberDiff line numberDiff line change
@@ -3,6 +3,7 @@
33
CPPCHECK_suppresses="--inline-suppr harness.c --suppress=unmatchedSuppression:harness.c --suppress=missingIncludeSystem \
44
--suppress=unusedFunction:linenoise.c \
55
--suppress=ConfigurationNotChecked:random.c \
6+
--suppress=identicalInnerCondition:log2_lshift16.h \
67
--suppress=nullPointerRedundantCheck:report.c \
78
--suppress=nullPointerRedundantCheck:harness.c \
89
--suppress=nullPointer:qtest.c \

‎shannon_entropy.c

+34
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,34 @@
1+
#include <assert.h>
2+
#include <stdint.h>
3+
#include <string.h>
4+
5+
/* Precalculated log2 realization */
6+
#include "log2_lshift16.h"
7+
8+
/* Shannon full integer entropy calculation */
9+
#define BUCKET_SIZE (1 << 8)
10+
11+
double shannon_entropy(const uint8_t *s)
12+
{
13+
assert(s);
14+
const uint64_t count = strlen((char *) s);
15+
uint64_t entropy_sum = 0;
16+
const uint64_t entropy_max = 8 * LOG2_RET_SHIFT;
17+
18+
uint32_t bucket[256];
19+
memset(&bucket, 0, sizeof(bucket));
20+
21+
for (uint32_t i = 0; i < count; i++)
22+
bucket[s[i]]++;
23+
24+
for (uint32_t i = 0; i < BUCKET_SIZE; i++) {
25+
if (bucket[i]) {
26+
uint64_t p = bucket[i];
27+
p *= LOG2_ARG_SHIFT / count;
28+
entropy_sum += -p * log2_lshift16(p);
29+
}
30+
}
31+
32+
entropy_sum /= LOG2_ARG_SHIFT;
33+
return entropy_sum * 100.0 / entropy_max;
34+
}

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