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egismoc: Simplify check bytes computation

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We use big endian values for generating the check bytes, but we can do
the same logic in a simpler way.
This commit is contained in:
Marco Trevisan (Treviño)
2024-02-19 21:41:44 +01:00
parent 6768bd0ff4
commit 59dc585ccd
1 changed files with 10 additions and 8 deletions
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18
libfprint/drivers/egismoc/egismoc.c
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@@ -293,19 +293,21 @@ egismoc_get_check_bytes (const guchar *value,
{ {
fp_dbg ("Get check bytes"); fp_dbg ("Get check bytes");
EgisMocCheckBytes check_bytes; EgisMocCheckBytes check_bytes;
guint16 big_endian_values[(int) ((value_length + 1) / 2)]; const size_t steps = (value_length + 1) / 2;
guint16 big_endian_values[steps];
size_t sum_values = 0; size_t sum_values = 0;
int s = 0;
for (int i = 0; i < value_length; i = i + 2, s++) for (int i = 0, j = 0; i < value_length; i += 2, j++)
{ {
if (i + 1 < value_length) big_endian_values[j] = 0;
big_endian_values[s] = (((guint16) value[i + 1]) << 8) | (0x00ff & value[i]);
else if (i < value_length - 1)
big_endian_values[s] = (((guint16) 0x00) << 8) | (0x00ff & value[i]); big_endian_values[j] = value[i + 1] << 8;
big_endian_values[j] |= (value[i] & 0x00ff);
} }
for (int i = 0; i < s; i++) for (int i = 0; i < steps; i++)
sum_values += big_endian_values[i]; sum_values += big_endian_values[i];
check_bytes.check_value = 0xffff - (sum_values % 0xffff); check_bytes.check_value = 0xffff - (sum_values % 0xffff);