Jerry/bird
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity

Fletcher16 test fixed to work at bigendian architectures.

Browse source 
To be honest, it was wrong in concept, anyway it accidentally worked.
This commit is contained in:
Maria Matejka 2020-04-05 01:12:06 +02:00
parent c9d11e6230
commit 2928c5bcc7
1 changed files with 21 additions and 10 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

31
lib/fletcher16_test.c
View file

@ -24,24 +24,33 @@ straightforward_fletcher16_compute(const char *data)
sum2 = (sum2 + sum1) % 255; sum2 = (sum2 + sum1) % 255;
} }
return (sum2 << 8) | sum1; sum2 = (sum2 + sum1) % 255;
sum2 = (sum2 + sum1) % 255;
return (sum1 << 8) | sum2;
} }
static u16 static u16
straightforward_fletcher16_checksum(const char *data) straightforward_fletcher16_checksum(const char *data)
{ {
u16 csum; u16 csum;
u8 c0,c1,f0,f1; u16 c0,c1,x,y;
csum = straightforward_fletcher16_compute(data); csum = straightforward_fletcher16_compute(data);
f0 = csum & 0xff; c0 = (csum >> 8) & 0xff;
f1 = (csum >> 8) & 0xff; c1 = csum & 0xff;
c0 = 0xff - ((f0 + f1) % 0xff);
c1 = 0xff - ((f0 + c0) % 0xff);
return (c1 << 8) | c0; x = (255 + c0 - c1) % 255;
y = (510 - 2*c0 + c1) % 255;
if (!x) x = 255;
if (!y) y = 255;
return (x << 8) | y;
} }
const u8 zero16[2] = {};
static int static int
test_fletcher16(void *out_, const void *in_, const void *expected_out_) test_fletcher16(void *out_, const void *in_, const void *expected_out_)
{ {
@ -53,7 +62,8 @@ test_fletcher16(void *out_, const void *in_, const void *expected_out_)
fletcher16_init(&ctxt); fletcher16_init(&ctxt);
fletcher16_update(&ctxt, in, strlen(in)); fletcher16_update(&ctxt, in, strlen(in));
put_u16(out, fletcher16_compute(&ctxt)); fletcher16_update(&ctxt, zero16, 2);
*out = fletcher16_compute(&ctxt);
return *out == *expected_out; return *out == *expected_out;
} }
@ -70,7 +80,8 @@ test_fletcher16_checksum(void *out_, const void *in_, const void *expected_out_)
fletcher16_init(&ctxt); fletcher16_init(&ctxt);
fletcher16_update(&ctxt, in, len); fletcher16_update(&ctxt, in, len);
put_u16(out, fletcher16_final(&ctxt, len, len)); fletcher16_update(&ctxt, zero16, 2);
*out = fletcher16_final(&ctxt, len+2, len);
return *out == *expected_out; return *out == *expected_out;
} }
@ -81,7 +92,7 @@ t_fletcher16_compute(void)
struct bt_pair test_vectors[] = { struct bt_pair test_vectors[] = {
{ {
.in = "\001\002", .in = "\001\002",
.out = & (const u16) { 0x0403 }, .out = & ((const u16) { straightforward_fletcher16_compute("\001\002") }),
}, },
{ {
.in = "", .in = "",