ols: Don't store temporary data in device context

[libsigrok.git] / HACKING

diff --git a/HACKING b/HACKING
index 0e818c2116d718c0703e1dceda4ecd06ed333e10..9d71c55c11d0fa240b7eb3b5f32b83e0b20a095c 100644 (file)
--- a/HACKING
+++ b/HACKING
@@ -5,8 +5,9 @@ HACKING
 Coding style
 ------------
 
 Coding style
 ------------
 

-This project is programmed using the Linux kernel coding style, see
-http://lxr.linux.no/linux/Documentation/CodingStyle for details.
+This project is programmed using the Linux kernel coding style:
+
+  https://www.kernel.org/doc/html/latest/process/coding-style.html

 
 Please use the same style for any code contributions, thanks!
 
 
 Please use the same style for any code contributions, thanks!
 


@@ -14,15 +15,16 @@ Please use the same style for any code contributions, thanks!
 Contributions
 -------------
 
 Contributions
 -------------
 

- - Patches should be sent to the development mailinglist at
+ - In order to contribute you should ideally clone the git repository and
+   let us know (preferably via IRC, or via the mailing list) from where to
+   pull/review your changes. You can use github.com, or any other public git
+   hosting site.
+
+ - Alternatively, patches can be sent to the development mailinglist at

    sigrok-devel@lists.sourceforge.net (please subscribe to the list first).
 
    https://lists.sourceforge.net/lists/listinfo/sigrok-devel
 
    sigrok-devel@lists.sourceforge.net (please subscribe to the list first).
 
    https://lists.sourceforge.net/lists/listinfo/sigrok-devel
 

- - Alternatively, you can also clone the git repository and let us know
-   from where to pull/review your changes. You can use gitorious.org,
-   github.com, or any other public git hosting site.
-

 
 Adding a new hardware driver
 ----------------------------
 
 Adding a new hardware driver
 ----------------------------


@@ -45,7 +47,7 @@ You can apply it like this:
  $ cd libsigrok
  $ git am 0001-tondaj-sl-814-Initial-driver-skeleton.patch
 
  $ cd libsigrok
  $ git am 0001-tondaj-sl-814-Initial-driver-skeleton.patch
 

-You can now edit the files in the hardware/tondaj-sl-814 directory as needed
+You can now edit the files in src/hardware/tondaj-sl-814 as needed

 and implement your driver based on the skeleton files there. That means your
 patch submission later will consist of at least two patches: the initial one
 adding the skeleton driver, and one or more additional patches that actually
 and implement your driver based on the skeleton files there. That means your
 patch submission later will consist of at least two patches: the initial one
 adding the skeleton driver, and one or more additional patches that actually


@@ -59,15 +61,11 @@ This is a rough overview of what you need to do in order to add a new driver
 (using the Tondaj SL-814 device as example). It's basically what the
 'new-driver' script (see above) does for you:
 
 (using the Tondaj SL-814 device as example). It's basically what the
 'new-driver' script (see above) does for you:
 

- - configure.ac:
-   - Add an --enable-tondaj-sl-814 option.
-   - Add "hardware/tondaj-sl-814/Makefile" to the AC_CONFIG_FILES list.
-   - Add and entry for the device in the "Enabled hardware drivers" list
-     at the bottom of the file.
- - hardware/Makefile.am: Add "tondaj-sl-814" to the SUBDIRS variable.
- - hwdriver.c: Add a tondaj_sl_814_driver_info entry in two places.
- - hardware/tondaj-sl-814/ directory: Add the following files:
-   Makefile.am, api.c, protocol.c, protocol.h
+ - Makefile.am: Add to src_libdrivers_la_SOURCES under the HW_TONDAJ_SL_814
+   condition.
+ - configure.ac: Add an SR_DRIVER() call.
+ - src/drivers.c: Add a tondaj_sl_814_driver_info entry in two places.
+ - src/hardware/tondaj-sl-814/ directory: Add api.c, protocol.c, protocol.h.

 
 See existing drivers or the 'new-driver' output for the details.
 
 
 See existing drivers or the 'new-driver' output for the details.
 


@@ -81,18 +79,21 @@ Random notes
  - Generally avoid assigning values to variables at declaration time,
    especially so for complex and/or run-time dependent values.
 
  - Generally avoid assigning values to variables at declaration time,
    especially so for complex and/or run-time dependent values.
 

- - Consistently use g_try_malloc() / g_try_malloc0(). Do not use standard
+ - Consistently use g_*malloc() / g_*malloc0(). Do not use standard

    malloc()/calloc() if it can be avoided (sometimes other libs such
    as libftdi can return malloc()'d memory, for example).
 
  - Always properly match allocations with the proper *free() functions. If
    malloc()/calloc() if it can be avoided (sometimes other libs such
    as libftdi can return malloc()'d memory, for example).
 
  - Always properly match allocations with the proper *free() functions. If

-   glib's g_try_malloc()/g_try_malloc0() was used, use g_free() to free the
+   glib's g_*malloc()/g_*malloc0() was used, use g_free() to free the

    memory. Otherwise use standard free(). Never use the wrong function!
 
    memory. Otherwise use standard free(). Never use the wrong function!
 

- - Never use g_malloc() or g_malloc0(). These functions do not return NULL
-   if not enough memory is available but rather lead to an exit() or segfault
-   instead. This behaviour is not acceptable for libraries.
-   Use g_try_malloc()/g_try_malloc0() instead and check the return value.
+ - We assume that "small" memory allocations (< 1MB) will always succeed.
+   Thus, it's fine to use g_malloc() or g_malloc0() for allocations of
+   simple/small structs and such (instead of using g_try_malloc()), and
+   there's no need to check the return value.
+
+   Do use g_try_malloc() or g_try_malloc0() for large (>= 1MB) allocations
+   and check the return value.

 
  - You should never print any messages (neither to stdout nor stderr nor
    elsewhere) "manually" via e.g. printf() or g_log() or similar functions.
 
  - You should never print any messages (neither to stdout nor stderr nor
    elsewhere) "manually" via e.g. printf() or g_log() or similar functions.


@@ -105,7 +106,7 @@ Random notes
  - Consistently use the same naming convention for #include guards in headers:
    <PROJECTNAME>_<PATH_TO_FILE>_<FILE>
    This ensures that all #include guards are always unique and consistent.
  - Consistently use the same naming convention for #include guards in headers:
    <PROJECTNAME>_<PATH_TO_FILE>_<FILE>
    This ensures that all #include guards are always unique and consistent.

-   Examples: LIBSIGROK_LIBSIGROK_H, LIBSIGROK_HARDWARE_MIC_985XX_PROTOCOL_H
+   Example: LIBSIGROK_HARDWARE_MIC_985XX_PROTOCOL_H

 
  - Consistently use the same naming convention for API functions:
    <libprefix>_<groupname>_<action>().
 
  - Consistently use the same naming convention for API functions:
    <libprefix>_<groupname>_<action>().


@@ -141,13 +142,31 @@ Random notes
 Doxygen
 -------
 
 Doxygen
 -------
 

+ - Use the @ notation for all Doxygen comments (e.g. @param, not \param).
+
+ - Do not use the @brief tag, it's unnecessary as we use JAVADOC_AUTOBRIEF.
+
+ - Generally use the following item order in Doxygen comments:
+    - Brief function description (1 line), followed by an empty line.
+    - Optionally, a longer function description (and another empty line).
+    - The list of parameter descriptions (@param).
+    - The return value description (@return or @retval).
+    - An optional @since tag (only for public SR_API functions).
+    - An optional @private tag (for private SR_PRIV functions).
+
+ - In @param lines, the name of the parameter is followed by a space and
+   then a sentence describing the parameter (starts with a capital letter,
+   ends with a full stop).
+

  - In Doxygen comments, put an empty line between the block of @param lines
    and the final @return line. The @param lines themselves (if there is more
    than one) are not separated by empty lines.
 
  - Mark private functions (SR_PRIV) with /** @private */, so that Doxygen
    doesn't include them in the output. Functions that are "static" anyway
  - In Doxygen comments, put an empty line between the block of @param lines
    and the final @return line. The @param lines themselves (if there is more
    than one) are not separated by empty lines.
 
  - Mark private functions (SR_PRIV) with /** @private */, so that Doxygen
    doesn't include them in the output. Functions that are "static" anyway

-   don't need to be marked like this.
+   don't need to be marked like this. Functions in non-public files that
+   are explicitly excluded in Doxyfile don't need to be marked either.
+   Don't use @internal, always use @private instead.

 
  - Mark private variables/#defines with /** @cond PRIVATE */ and
    /** @endcond */, so that Doxygen doesn't include them in the output.
 
  - Mark private variables/#defines with /** @cond PRIVATE */ and
    /** @endcond */, so that Doxygen doesn't include them in the output.


@@ -168,6 +187,58 @@ Doxygen
    The @since tag should be the last one, i.e. it should come after @param,
    @return, @see, and so on.
 
    The @since tag should be the last one, i.e. it should come after @param,
    @return, @see, and so on.
 

+ - Examples:
+
+/**
+ * Tell a hardware driver to scan for devices.
+ *
+ * In addition to the detection, the devices that are found are also
+ * initialized automatically. On some devices, this involves a firmware upload,
+ * or other such measures.
+ *
+ * The order in which the system is scanned for devices is not specified. The
+ * caller should not assume or rely on any specific order.
+ *
+ * Before calling sr_driver_scan(), the user must have previously initialized
+ * the driver by calling sr_driver_init().
+ *
+ * @param[in] driver The driver that should scan. Must be a pointer to one of
+ *                   the entries returned by sr_driver_list(). Must not be NULL.
+ * @param[in] options List of 'struct sr_hwopt' options to pass to the driver's
+ *                    scanner. Can be NULL/empty.
+ *
+ * @return A GSList * of 'struct sr_dev_inst', or NULL if no devices were
+ *         found (or errors were encountered). This list must be freed by the
+ *         caller using g_slist_free(), but without freeing the data pointed
+ *         to in the list.
+ *
+ * @since 0.2.0
+ */
+
+/**
+ * Query value of a configuration key at the given driver or device instance.
+ *
+ * @param[in] driver The sr_dev_driver struct to query. Must not be NULL.
+ * @param[in] sdi (optional) If the key is specific to a device, this must
+ *            contain a pointer to the struct sr_dev_inst to be checked.
+ *            Otherwise it must be NULL. If sdi is != NULL, sdi->priv must
+ *            also be != NULL.
+ * @param[in,out] data Pointer to a GVariant where the value will be stored.
+ *             Must not be NULL. The caller is given ownership of the GVariant
+ *             and must thus decrease the refcount after use. However if
+ *             this function returns an error code, the field should be
+ *             considered unused, and should not be unreferenced.
+ *
+ * @retval SR_OK Success.
+ * @retval SR_ERR Error.
+ * @retval SR_ERR_ARG The driver doesn't know that key, but this is not to be
+ *         interpreted as an error by the caller; merely as an indication
+ *         that it's not applicable.
+ *
+ * @since 0.3.0
+ * @private
+ */
+

 
 Testsuite
 ---------
 
 Testsuite
 ---------