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Correct return values for I2C::write(int, const char*, int, bool) #3827

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Mar 14, 2017
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Correct return values for I2C::write(int, const char*, int, bool) #3827

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4 changes: 2 additions & 2 deletions drivers/I2C.h
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Original file line number Diff line number Diff line change
Expand Up @@ -117,8 +117,8 @@ class I2C {
* @param repeated Repeated start, true - do not send stop at end
*
* @returns
* 0 or non-zero - written number of bytes,
* negative - I2C_ERROR_XXX status
* 0 on success (ack),
* non-0 on failure (nack)
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I recall this was updated not that long ago. Is a positive number really a failure?

This came from i2c HAL write that specifies the following:

`/** Blocking sending data
 *
 *  @param obj     The I2C object
 *  @param address 7-bit address (last bit is 0)
 *  @param data    The buffer for sending
 *  @param length  Number of bytes to write
 *  @param stop    Stop to be generated after the transfer is done
 *  @return 
 *      zero or non-zero - Number of written bytes
 *      negative - I2C_ERROR_XXX status
 */
int i2c_write(i2c_t *obj, int address, const char *data, int length, int stop);

How many targets do follow this new update? how does it map to the current one?

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@betzw betzw Feb 23, 2017 •
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Well, there a two different methods/functions: one is
method I2C::write(int, const char*, int, bool) declared in drivers/I2C.h,
the other one is
function i2c_write(i2c_t*, int, const char, int, int) declared in hal/i2c_api.h.

Method I2C::write(int, const char*, int, bool) uses function i2c_write(i2c_t*, int, const char, int, int) to implement its functionality (see here, especially line #66).

In particular note that the return value of method I2C::write(int, const char*, int, bool) is computed in this line ... and is different from the return value of function i2c_write(i2c_t*, int, const char, int, int)!

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thanks, that explains it

*/
int write(int address, const char *data, int length, bool repeated = false);

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