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Fletcher16 test fixed to work at bigendian architectures.

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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
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31
lib/fletcher16_test.c
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@ -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 = "",