From: Mauro Carvalho Chehab Date: Mon, 25 May 2015 19:44:40 +0000 (-0300) Subject: [media] DocBook: move DVBv3 frontend bits to a separate section X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=a8d3e4b4d9298bdc36934a0b49a7d540d8eaf8f9;p=linux-beck.git [media] DocBook: move DVBv3 frontend bits to a separate section Although the recommended usage is the DVBv5 API calls, the documentation doesn't make it clear about what's the recommended calls and what's legacy. So, move the legacy API bits to a separate xml, putting them into a new section. Please notice that more changes are needed, since some of the bits there are cross-referenced elsewhere. Signed-off-by: Mauro Carvalho Chehab --- diff --git a/Documentation/DocBook/media/dvb/frontend.xml b/Documentation/DocBook/media/dvb/frontend.xml index 98443c4c2818..3b3973aee8eb 100644 --- a/Documentation/DocBook/media/dvb/frontend.xml +++ b/Documentation/DocBook/media/dvb/frontend.xml @@ -29,58 +29,6 @@ specification is available at Eutelsat. -
-Frontend Data Types - -
-Frontend type - -For historical reasons, frontend types are named by the type of modulation - used in transmission. The fontend types are given by fe_type_t type, defined as: - - -Frontend types - - &cs-def; - - - fe_type - Description - DTV_DELIVERY_SYSTEM equivalent type - - - - - FE_QPSK - For DVB-S standard - SYS_DVBS - - - FE_QAM - For DVB-C annex A standard - SYS_DVBC_ANNEX_A - - - FE_OFDM - For DVB-T standard - SYS_DVBT - - - FE_ATSC - For ATSC standard (terrestrial) or for DVB-C Annex B (cable) used in US. - SYS_ATSC (terrestrial) or SYS_DVBC_ANNEX_B (cable) - -
- -Newer formats like DVB-S2, ISDB-T, ISDB-S and DVB-T2 are not described at the above, as they're -supported via the new FE_GET_PROPERTY/FE_GET_SET_PROPERTY ioctl's, using the DTV_DELIVERY_SYSTEM parameter. - - -The usage of this field is deprecated, as it doesn't report all supported standards, and -will provide an incomplete information for frontends that support multiple delivery systems. -Please use DTV_ENUM_DELSYS instead. -
-
frontend capabilities @@ -157,6 +105,7 @@ a specific frontend type. };
+
diseqc slave reply @@ -258,90 +207,8 @@ typedef enum fe_status { recommended to reset DiSEqC, tone and parameters -
-
-frontend parameters -The kind of parameters passed to the frontend device for tuning depend on -the kind of hardware you are using. -The struct dvb_frontend_parameters uses an -union with specific per-system parameters. However, as newer delivery systems -required more data, the structure size weren't enough to fit, and just -extending its size would break the existing applications. So, those parameters -were replaced by the usage of -FE_GET_PROPERTY/FE_SET_PROPERTY ioctl's. The -new API is flexible enough to add new parameters to existing delivery systems, -and to add newer delivery systems. -So, newer applications should use -FE_GET_PROPERTY/FE_SET_PROPERTY instead, in -order to be able to support the newer System Delivery like DVB-S2, DVB-T2, -DVB-C2, ISDB, etc. -All kinds of parameters are combined as an union in the FrontendParameters structure: - -struct dvb_frontend_parameters { - uint32_t frequency; /⋆ (absolute) frequency in Hz for QAM/OFDM ⋆/ - /⋆ intermediate frequency in kHz for QPSK ⋆/ - fe_spectral_inversion_t inversion; - union { - struct dvb_qpsk_parameters qpsk; - struct dvb_qam_parameters qam; - struct dvb_ofdm_parameters ofdm; - struct dvb_vsb_parameters vsb; - } u; -}; - -In the case of QPSK frontends the frequency field specifies the intermediate -frequency, i.e. the offset which is effectively added to the local oscillator frequency (LOF) of -the LNB. The intermediate frequency has to be specified in units of kHz. For QAM and -OFDM frontends the frequency specifies the absolute frequency and is given in Hz. - - -
-QPSK parameters -For satellite QPSK frontends you have to use the dvb_qpsk_parameters structure: - - struct dvb_qpsk_parameters { - uint32_t symbol_rate; /⋆ symbol rate in Symbols per second ⋆/ - fe_code_rate_t fec_inner; /⋆ forward error correction (see above) ⋆/ - }; - -
-
-QAM parameters -for cable QAM frontend you use the dvb_qam_parameters structure: - - struct dvb_qam_parameters { - uint32_t symbol_rate; /⋆ symbol rate in Symbols per second ⋆/ - fe_code_rate_t fec_inner; /⋆ forward error correction (see above) ⋆/ - fe_modulation_t modulation; /⋆ modulation type (see above) ⋆/ - }; - -
-
-VSB parameters -ATSC frontends are supported by the dvb_vsb_parameters structure: - -struct dvb_vsb_parameters { - fe_modulation_t modulation; /⋆ modulation type (see above) ⋆/ -}; - -
-
-OFDM parameters -DVB-T frontends are supported by the dvb_ofdm_parameters structure: - - struct dvb_ofdm_parameters { - fe_bandwidth_t bandwidth; - fe_code_rate_t code_rate_HP; /⋆ high priority stream code rate ⋆/ - fe_code_rate_t code_rate_LP; /⋆ low priority stream code rate ⋆/ - fe_modulation_t constellation; /⋆ modulation type (see above) ⋆/ - fe_transmit_mode_t transmission_mode; - fe_guard_interval_t guard_interval; - fe_hierarchy_t hierarchy_information; - }; - -
frontend spectral inversion The Inversion field can take one of these values: @@ -358,6 +225,7 @@ typedef enum fe_spectral_inversion { itself.
+
frontend code rate The possible values for the fec_inner field used on @@ -384,6 +252,7 @@ typedef enum fe_code_rate { detection.
+
frontend modulation type for QAM, OFDM and VSB For cable and terrestrial frontends, e. g. for @@ -410,8 +279,10 @@ it needs to specify the quadrature modulation mode which can be one of the follo } fe_modulation_t;
+
More OFDM parameters +
Number of carriers per channel @@ -426,6 +297,7 @@ typedef enum fe_transmit_mode { } fe_transmit_mode_t;
+
frontend bandwidth @@ -440,6 +312,7 @@ typedef enum fe_bandwidth { } fe_bandwidth_t;
+
frontend guard inverval @@ -455,6 +328,7 @@ typedef enum fe_guard_interval { } fe_guard_interval_t;
+
frontend hierarchy @@ -466,23 +340,10 @@ typedef enum fe_hierarchy { HIERARCHY_AUTO } fe_hierarchy_t; -
-
-
-
-frontend events - - struct dvb_frontend_event { - fe_status_t status; - struct dvb_frontend_parameters parameters; - }; - -
-
Frontend Function Calls @@ -694,417 +555,6 @@ typedef enum fe_hierarchy {
-
-FE_READ_BER -DESCRIPTION - - -This ioctl call returns the bit error rate for the signal currently - received/demodulated by the front-end. For this command, read-only access to - the device is sufficient. - - -SYNOPSIS - - -int ioctl(int fd, int request = FE_READ_BER, - uint32_t ⋆ber); - - -PARAMETERS - - -int fd - -File descriptor returned by a previous call to open(). - - -int request - -Equals FE_READ_BER for this command. - - -uint32_t *ber - -The bit error rate is stored into *ber. - - - -&return-value-dvb; -
- -
-FE_READ_SNR - -DESCRIPTION - - -This ioctl call returns the signal-to-noise ratio for the signal currently received - by the front-end. For this command, read-only access to the device is sufficient. - - -SYNOPSIS - - -int ioctl(int fd, int request = FE_READ_SNR, uint16_t - ⋆snr); - - -PARAMETERS - - -int fd - -File descriptor returned by a previous call to open(). - - -int request - -Equals FE_READ_SNR for this command. - - -uint16_t *snr - -The signal-to-noise ratio is stored into *snr. - - - -&return-value-dvb; -
- -
-FE_READ_SIGNAL_STRENGTH -DESCRIPTION - - -This ioctl call returns the signal strength value for the signal currently received - by the front-end. For this command, read-only access to the device is sufficient. - - -SYNOPSIS - - -int ioctl( int fd, int request = - FE_READ_SIGNAL_STRENGTH, uint16_t ⋆strength); - - - -PARAMETERS - - -int fd - -File descriptor returned by a previous call to open(). - - -int request - -Equals FE_READ_SIGNAL_STRENGTH for this - command. - - -uint16_t *strength - -The signal strength value is stored into *strength. - - - -&return-value-dvb; -
- -
-FE_READ_UNCORRECTED_BLOCKS -DESCRIPTION - - -This ioctl call returns the number of uncorrected blocks detected by the device - driver during its lifetime. For meaningful measurements, the increment in block - count during a specific time interval should be calculated. For this command, - read-only access to the device is sufficient. - - -Note that the counter will wrap to zero after its maximum count has been - reached. - - -SYNOPSIS - - -int ioctl( int fd, int request = - FE_READ_UNCORRECTED_BLOCKS, uint32_t ⋆ublocks); - - -PARAMETERS - - -int fd - -File descriptor returned by a previous call to open(). - - -int request - -Equals FE_READ_UNCORRECTED_BLOCKS for this - command. - - -uint32_t *ublocks - -The total number of uncorrected blocks seen by the driver - so far. - - - -&return-value-dvb; -
- -
-FE_SET_FRONTEND -DESCRIPTION - - -This ioctl call starts a tuning operation using specified parameters. The result - of this call will be successful if the parameters were valid and the tuning could - be initiated. The result of the tuning operation in itself, however, will arrive - asynchronously as an event (see documentation for FE_GET_EVENT and - FrontendEvent.) If a new FE_SET_FRONTEND operation is initiated before - the previous one was completed, the previous operation will be aborted in favor - of the new one. This command requires read/write access to the device. - - - -SYNOPSIS - - -int ioctl(int fd, int request = FE_SET_FRONTEND, - struct dvb_frontend_parameters ⋆p); - - -PARAMETERS - - -int fd - -File descriptor returned by a previous call to open(). - - -int request - -Equals FE_SET_FRONTEND for this command. - - -struct - dvb_frontend_parameters - *p - -Points to parameters for tuning operation. - - - -&return-value-dvb; - -EINVAL - -Maximum supported symbol rate reached. - - -
- -
-FE_GET_FRONTEND -DESCRIPTION - - -This ioctl call queries the currently effective frontend parameters. For this - command, read-only access to the device is sufficient. - - - -SYNOPSIS - - -int ioctl(int fd, int request = FE_GET_FRONTEND, - struct dvb_frontend_parameters ⋆p); - - - -PARAMETERS - - -int fd - -File descriptor returned by a previous call to open(). - - -int request - -Equals FE_SET_FRONTEND for this command. - - -struct - dvb_frontend_parameters - *p - -Points to parameters for tuning operation. - - - -&return-value-dvb; - -EINVAL - -Maximum supported symbol rate reached. - - - -
- -
-FE_GET_EVENT -DESCRIPTION - - -This ioctl call returns a frontend event if available. If an event is not - available, the behavior depends on whether the device is in blocking or - non-blocking mode. In the latter case, the call fails immediately with errno - set to EWOULDBLOCK. In the former case, the call blocks until an event - becomes available. - - -The standard Linux poll() and/or select() system calls can be used with the - device file descriptor to watch for new events. For select(), the file descriptor - should be included in the exceptfds argument, and for poll(), POLLPRI should - be specified as the wake-up condition. Since the event queue allocated is - rather small (room for 8 events), the queue must be serviced regularly to avoid - overflow. If an overflow happens, the oldest event is discarded from the queue, - and an error (EOVERFLOW) occurs the next time the queue is read. After - reporting the error condition in this fashion, subsequent - FE_GET_EVENT - calls will return events from the queue as usual. - - -For the sake of implementation simplicity, this command requires read/write - access to the device. - - - -SYNOPSIS - - -int ioctl(int fd, int request = QPSK_GET_EVENT, - struct dvb_frontend_event ⋆ev); - - - -PARAMETERS - - -int fd - -File descriptor returned by a previous call to open(). - - -int request - -Equals FE_GET_EVENT for this command. - - -struct - dvb_frontend_event - *ev - -Points to the location where the event, - - - -if any, is to be stored. - - - -&return-value-dvb; - -EWOULDBLOCK - -There is no event pending, and the device is in - non-blocking mode. - - -EOVERFLOW - -Overflow in event queue - one or more events were lost. - - -
-
FE_GET_INFO DESCRIPTION @@ -1521,40 +971,15 @@ FE_TUNE_MODE_ONESHOT When set, this flag will disable any zigzagging or other "n &return-value-dvb;
-
- FE_DISHNETWORK_SEND_LEGACY_CMD -DESCRIPTION - - -WARNING: This is a very obscure legacy command, used only at stv0299 driver. Should not be used on newer drivers. -It provides a non-standard method for selecting Diseqc voltage on the frontend, for Dish Network legacy switches. -As support for this ioctl were added in 2004, this means that such dishes were already legacy in 2004. - - - -SYNOPSIS - - -int ioctl(int fd, int request = - FE_DISHNETWORK_SEND_LEGACY_CMD, unsigned long cmd); - - - -PARAMETERS - - - unsigned long cmd - - - -sends the specified raw cmd to the dish via DISEqC. - - - - -&return-value-dvb;
+
+DVB Frontend legacy API (a. k. a. DVBv3) +The usage of this API is deprecated, as it doesn't support all digital + TV standards, doesn't provide good statistics measurements and provides + incomplete information. This is kept only to support legacy applications. + +&sub-frontend_legacy_api;
&sub-dvbproperty; diff --git a/Documentation/DocBook/media/dvb/frontend_legacy_api.xml b/Documentation/DocBook/media/dvb/frontend_legacy_api.xml new file mode 100644 index 000000000000..f4d300488d12 --- /dev/null +++ b/Documentation/DocBook/media/dvb/frontend_legacy_api.xml @@ -0,0 +1,603 @@ +
+Frontend Legacy Data Types + +
+Frontend type + +For historical reasons, frontend types are named by the type of modulation + used in transmission. The fontend types are given by fe_type_t type, defined as: + + +Frontend types + + &cs-def; + + + fe_type + Description + DTV_DELIVERY_SYSTEM equivalent type + + + + + FE_QPSK + For DVB-S standard + SYS_DVBS + + + FE_QAM + For DVB-C annex A standard + SYS_DVBC_ANNEX_A + + + FE_OFDM + For DVB-T standard + SYS_DVBT + + + FE_ATSC + For ATSC standard (terrestrial) or for DVB-C Annex B (cable) used in US. + SYS_ATSC (terrestrial) or SYS_DVBC_ANNEX_B (cable) + +
+ +Newer formats like DVB-S2, ISDB-T, ISDB-S and DVB-T2 are not described at the above, as they're +supported via the new FE_GET_PROPERTY/FE_GET_SET_PROPERTY ioctl's, using the DTV_DELIVERY_SYSTEM parameter. + + +The usage of this field is deprecated, as it doesn't report all supported standards, and +will provide an incomplete information for frontends that support multiple delivery systems. +Please use DTV_ENUM_DELSYS instead. +
+ + +
+frontend parameters +The kind of parameters passed to the frontend device for tuning depend on +the kind of hardware you are using. +The struct dvb_frontend_parameters uses an +union with specific per-system parameters. However, as newer delivery systems +required more data, the structure size weren't enough to fit, and just +extending its size would break the existing applications. So, those parameters +were replaced by the usage of +FE_GET_PROPERTY/FE_SET_PROPERTY ioctl's. The +new API is flexible enough to add new parameters to existing delivery systems, +and to add newer delivery systems. +So, newer applications should use +FE_GET_PROPERTY/FE_SET_PROPERTY instead, in +order to be able to support the newer System Delivery like DVB-S2, DVB-T2, +DVB-C2, ISDB, etc. +All kinds of parameters are combined as an union in the FrontendParameters structure: + +struct dvb_frontend_parameters { + uint32_t frequency; /⋆ (absolute) frequency in Hz for QAM/OFDM ⋆/ + /⋆ intermediate frequency in kHz for QPSK ⋆/ + fe_spectral_inversion_t inversion; + union { + struct dvb_qpsk_parameters qpsk; + struct dvb_qam_parameters qam; + struct dvb_ofdm_parameters ofdm; + struct dvb_vsb_parameters vsb; + } u; +}; + +In the case of QPSK frontends the frequency field specifies the intermediate +frequency, i.e. the offset which is effectively added to the local oscillator frequency (LOF) of +the LNB. The intermediate frequency has to be specified in units of kHz. For QAM and +OFDM frontends the frequency specifies the absolute frequency and is given in Hz. + + +
+QPSK parameters +For satellite QPSK frontends you have to use the dvb_qpsk_parameters structure: + + struct dvb_qpsk_parameters { + uint32_t symbol_rate; /⋆ symbol rate in Symbols per second ⋆/ + fe_code_rate_t fec_inner; /⋆ forward error correction (see above) ⋆/ + }; + +
+ +
+QAM parameters +for cable QAM frontend you use the dvb_qam_parameters structure: + + struct dvb_qam_parameters { + uint32_t symbol_rate; /⋆ symbol rate in Symbols per second ⋆/ + fe_code_rate_t fec_inner; /⋆ forward error correction (see above) ⋆/ + fe_modulation_t modulation; /⋆ modulation type (see above) ⋆/ + }; + +
+ +
+VSB parameters +ATSC frontends are supported by the dvb_vsb_parameters structure: + +struct dvb_vsb_parameters { + fe_modulation_t modulation; /⋆ modulation type (see above) ⋆/ +}; + +
+ +
+OFDM parameters +DVB-T frontends are supported by the dvb_ofdm_parameters structure: + + struct dvb_ofdm_parameters { + fe_bandwidth_t bandwidth; + fe_code_rate_t code_rate_HP; /⋆ high priority stream code rate ⋆/ + fe_code_rate_t code_rate_LP; /⋆ low priority stream code rate ⋆/ + fe_modulation_t constellation; /⋆ modulation type (see above) ⋆/ + fe_transmit_mode_t transmission_mode; + fe_guard_interval_t guard_interval; + fe_hierarchy_t hierarchy_information; + }; + +
+
+ +
+frontend events + + struct dvb_frontend_event { + fe_status_t status; + struct dvb_frontend_parameters parameters; + }; + +
+
+ +
+Frontend Legacy Function Calls + +Those functions are defined at DVB version 3. The support is kept in + the kernel due to compatibility issues only. Their usage is strongly + not recommended + +
+FE_READ_BER +DESCRIPTION + + +This ioctl call returns the bit error rate for the signal currently + received/demodulated by the front-end. For this command, read-only access to + the device is sufficient. + + +SYNOPSIS + + +int ioctl(int fd, int request = FE_READ_BER, + uint32_t ⋆ber); + + +PARAMETERS + + +int fd + +File descriptor returned by a previous call to open(). + + +int request + +Equals FE_READ_BER for this command. + + +uint32_t *ber + +The bit error rate is stored into *ber. + + + +&return-value-dvb; +
+ +
+FE_READ_SNR + +DESCRIPTION + + +This ioctl call returns the signal-to-noise ratio for the signal currently received + by the front-end. For this command, read-only access to the device is sufficient. + + +SYNOPSIS + + +int ioctl(int fd, int request = FE_READ_SNR, uint16_t + ⋆snr); + + +PARAMETERS + + +int fd + +File descriptor returned by a previous call to open(). + + +int request + +Equals FE_READ_SNR for this command. + + +uint16_t *snr + +The signal-to-noise ratio is stored into *snr. + + + +&return-value-dvb; +
+ +
+FE_READ_SIGNAL_STRENGTH +DESCRIPTION + + +This ioctl call returns the signal strength value for the signal currently received + by the front-end. For this command, read-only access to the device is sufficient. + + +SYNOPSIS + + +int ioctl( int fd, int request = + FE_READ_SIGNAL_STRENGTH, uint16_t ⋆strength); + + + +PARAMETERS + + +int fd + +File descriptor returned by a previous call to open(). + + +int request + +Equals FE_READ_SIGNAL_STRENGTH for this + command. + + +uint16_t *strength + +The signal strength value is stored into *strength. + + + +&return-value-dvb; +
+ +
+FE_READ_UNCORRECTED_BLOCKS +DESCRIPTION + + +This ioctl call returns the number of uncorrected blocks detected by the device + driver during its lifetime. For meaningful measurements, the increment in block + count during a specific time interval should be calculated. For this command, + read-only access to the device is sufficient. + + +Note that the counter will wrap to zero after its maximum count has been + reached. + + +SYNOPSIS + + +int ioctl( int fd, int request = + FE_READ_UNCORRECTED_BLOCKS, uint32_t ⋆ublocks); + + +PARAMETERS + + +int fd + +File descriptor returned by a previous call to open(). + + +int request + +Equals FE_READ_UNCORRECTED_BLOCKS for this + command. + + +uint32_t *ublocks + +The total number of uncorrected blocks seen by the driver + so far. + + + +&return-value-dvb; +
+ +
+FE_SET_FRONTEND +DESCRIPTION + + +This ioctl call starts a tuning operation using specified parameters. The result + of this call will be successful if the parameters were valid and the tuning could + be initiated. The result of the tuning operation in itself, however, will arrive + asynchronously as an event (see documentation for FE_GET_EVENT and + FrontendEvent.) If a new FE_SET_FRONTEND operation is initiated before + the previous one was completed, the previous operation will be aborted in favor + of the new one. This command requires read/write access to the device. + + + +SYNOPSIS + + +int ioctl(int fd, int request = FE_SET_FRONTEND, + struct dvb_frontend_parameters ⋆p); + + +PARAMETERS + + +int fd + +File descriptor returned by a previous call to open(). + + +int request + +Equals FE_SET_FRONTEND for this command. + + +struct + dvb_frontend_parameters + *p + +Points to parameters for tuning operation. + + + +&return-value-dvb; + +EINVAL + +Maximum supported symbol rate reached. + + +
+ +
+FE_GET_FRONTEND +DESCRIPTION + + +This ioctl call queries the currently effective frontend parameters. For this + command, read-only access to the device is sufficient. + + + +SYNOPSIS + + +int ioctl(int fd, int request = FE_GET_FRONTEND, + struct dvb_frontend_parameters ⋆p); + + + +PARAMETERS + + +int fd + +File descriptor returned by a previous call to open(). + + +int request + +Equals FE_SET_FRONTEND for this command. + + +struct + dvb_frontend_parameters + *p + +Points to parameters for tuning operation. + + + +&return-value-dvb; + +EINVAL + +Maximum supported symbol rate reached. + + + +
+ +
+FE_GET_EVENT +DESCRIPTION + + +This ioctl call returns a frontend event if available. If an event is not + available, the behavior depends on whether the device is in blocking or + non-blocking mode. In the latter case, the call fails immediately with errno + set to EWOULDBLOCK. In the former case, the call blocks until an event + becomes available. + + +The standard Linux poll() and/or select() system calls can be used with the + device file descriptor to watch for new events. For select(), the file descriptor + should be included in the exceptfds argument, and for poll(), POLLPRI should + be specified as the wake-up condition. Since the event queue allocated is + rather small (room for 8 events), the queue must be serviced regularly to avoid + overflow. If an overflow happens, the oldest event is discarded from the queue, + and an error (EOVERFLOW) occurs the next time the queue is read. After + reporting the error condition in this fashion, subsequent + FE_GET_EVENT + calls will return events from the queue as usual. + + +For the sake of implementation simplicity, this command requires read/write + access to the device. + + + +SYNOPSIS + + +int ioctl(int fd, int request = QPSK_GET_EVENT, + struct dvb_frontend_event ⋆ev); + + + +PARAMETERS + + +int fd + +File descriptor returned by a previous call to open(). + + +int request + +Equals FE_GET_EVENT for this command. + + +struct + dvb_frontend_event + *ev + +Points to the location where the event, + + + +if any, is to be stored. + + + +&return-value-dvb; + +EWOULDBLOCK + +There is no event pending, and the device is in + non-blocking mode. + + +EOVERFLOW + +Overflow in event queue - one or more events were lost. + + +
+ +
+ FE_DISHNETWORK_SEND_LEGACY_CMD +DESCRIPTION + + +WARNING: This is a very obscure legacy command, used only at stv0299 driver. Should not be used on newer drivers. +It provides a non-standard method for selecting Diseqc voltage on the frontend, for Dish Network legacy switches. +As support for this ioctl were added in 2004, this means that such dishes were already legacy in 2004. + + + +SYNOPSIS + + +int ioctl(int fd, int request = + FE_DISHNETWORK_SEND_LEGACY_CMD, unsigned long cmd); + + + +PARAMETERS + + + unsigned long cmd + + + +sends the specified raw cmd to the dish via DISEqC. + + + + +&return-value-dvb; +
+ +