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egismoc: Use FpiByteReader to compute the check bytes

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We can read the values in the proper format without having to
deal with endianness ourself, so let's do this instead of manual
labor.
This commit is contained in:
Marco Trevisan (Treviño)
2024-02-20 17:46:57 +01:00
parent e055781006
commit 666cd0c08d
1 changed files with 9 additions and 23 deletions
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32
libfprint/drivers/egismoc/egismoc.c
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@@ -277,28 +277,18 @@ egismoc_cmd_ssm_done (FpiSsm *ssm,
* should be 0, otherwise the device will reject the payload
*/
static guint16
egismoc_get_check_bytes (const guchar *value,
const gsize value_length)
egismoc_get_check_bytes (FpiByteReader *reader)
{
fp_dbg ("Get check bytes");
const size_t steps = (value_length + 1) / 2;
guint16 values[steps];
size_t sum_values = 0;
guint16 val;
g_assert (value);
fpi_byte_reader_set_pos (reader, 0);
for (int i = 0, j = 0; i < value_length; i += 2, j++)
{
values[j] = (value[i] << 8 & 0xff00);
while (fpi_byte_reader_get_uint16_be (reader, &val))
sum_values += val;
if (i < value_length - 1)
values[j] |= value[i + 1] & 0x00ff;
}
for (int i = 0; i < steps; i++)
sum_values += values[i];
return 0xffff - (sum_values % 0xffff);
return G_MAXUINT16 - (sum_values % G_MAXUINT16);
}
static void
@@ -311,7 +301,6 @@ egismoc_exec_cmd (FpDevice *device,
g_auto(FpiByteWriter) writer = {0};
g_autoptr(FpiUsbTransfer) transfer = NULL;
FpiDeviceEgisMoc *self = FPI_DEVICE_EGISMOC (device);
const guint8 *buffer_out = NULL;
g_autofree CommandData *data = NULL;
gsize buffer_out_length = 0;
gboolean written = TRUE;
@@ -331,7 +320,8 @@ egismoc_exec_cmd (FpDevice *device,
+ EGISMOC_CHECK_BYTES_LENGTH
+ cmd_length;
fpi_byte_writer_init_with_size (&writer, buffer_out_length, TRUE);
fpi_byte_writer_init_with_size (&writer, buffer_out_length +
(buffer_out_length % 2 ? 1 : 0), TRUE);
/* Prefix */
written &= fpi_byte_writer_put_data (&writer, egismoc_write_prefix,
@@ -346,11 +336,7 @@ egismoc_exec_cmd (FpDevice *device,
/* Now fetch and set the "real" check bytes based on the currently
* assembled payload */
fpi_byte_reader_set_pos (FPI_BYTE_READER (&writer), 0);
written &= fpi_byte_reader_peek_data (FPI_BYTE_READER (&writer),
buffer_out_length, &buffer_out);
check_value = egismoc_get_check_bytes (buffer_out, buffer_out_length);
check_value = egismoc_get_check_bytes (FPI_BYTE_READER (&writer));
fpi_byte_writer_set_pos (&writer, egismoc_write_prefix_len);
written &= fpi_byte_writer_put_uint16_be (&writer, check_value);