84d35492b1
Inheritance of HAL object is performed by composing a child structure of a
single parent structure located at offset 0 followed by new data members
and function pointers in the child structure.
For example,
struct child {
struct parent common;
int a_data_member;
void (*a_method)(struct child *c, int v);
};
HAL code assumes this layout when accessing child structures given a pointer
to a parent structure such that users write code like the following...
void child_method(struct *parent, int v) {
struct child * c = (struct child*)parent;
// do stuff with c
}
Code above will break if a member is added before "common" in "struct child".
This change adds comments that describe the restriction on the location of
parent HAL objects within a derived HAL object. HAL objects that already
have comments that describe the required location of parent objects are not
modified.
Change-Id: Ibe4300275286ef275b2097534c84f1029d761d87
92 lines
3.5 KiB
C
92 lines
3.5 KiB
C
/*
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* Copyright (C) 2013 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef ANDROID_INCLUDE_HARDWARE_CONSUMERIR_H
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#define ANDROID_INCLUDE_HARDWARE_CONSUMERIR_H
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#include <stdint.h>
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#include <sys/cdefs.h>
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#include <hardware/hardware.h>
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#include <hardware/hwcomposer_defs.h>
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#define CONSUMERIR_MODULE_API_VERSION_1_0 HARDWARE_MODULE_API_VERSION(1, 0)
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#define CONSUMERIR_HARDWARE_MODULE_ID "consumerir"
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#define CONSUMERIR_TRANSMITTER "transmitter"
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typedef struct consumerir_freq_range {
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int min;
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int max;
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} consumerir_freq_range_t;
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typedef struct consumerir_module {
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/**
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* Common methods of the consumer IR module. This *must* be the first member of
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* consumerir_module as users of this structure will cast a hw_module_t to
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* consumerir_module pointer in contexts where it's known the hw_module_t references a
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* consumerir_module.
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*/
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struct hw_module_t common;
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} consumerir_module_t;
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typedef struct consumerir_device {
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/**
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* Common methods of the consumer IR device. This *must* be the first member of
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* consumerir_device as users of this structure will cast a hw_device_t to
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* consumerir_device pointer in contexts where it's known the hw_device_t references a
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* consumerir_device.
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*/
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struct hw_device_t common;
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/*
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* (*transmit)() is called to by the ConsumerIrService to send an IR pattern
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* at a given carrier_freq.
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*
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* The pattern is alternating series of carrier on and off periods measured in
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* microseconds. The carrier should be turned off at the end of a transmit
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* even if there are and odd number of entries in the pattern array.
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*
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* This call should return when the transmit is complete or encounters an error.
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*
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* returns: 0 on success. A negative error code on error.
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*/
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int (*transmit)(struct consumerir_device *dev, int carrier_freq,
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const int pattern[], int pattern_len);
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/*
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* (*get_num_carrier_freqs)() is called by the ConsumerIrService to get the
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* number of carrier freqs to allocate space for, which is then filled by
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* a subsequent call to (*get_carrier_freqs)().
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*
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* returns: the number of ranges on success. A negative error code on error.
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*/
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int (*get_num_carrier_freqs)(struct consumerir_device *dev);
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/*
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* (*get_carrier_freqs)() is called by the ConsumerIrService to enumerate
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* which frequencies the IR transmitter supports. The HAL implementation
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* should fill an array of consumerir_freq_range structs with the
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* appropriate values for the transmitter, up to len elements.
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*
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* returns: the number of ranges on success. A negative error code on error.
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*/
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int (*get_carrier_freqs)(struct consumerir_device *dev,
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size_t len, consumerir_freq_range_t *ranges);
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/* Reserved for future use. Must be NULL. */
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void* reserved[8 - 3];
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} consumerir_device_t;
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#endif /* ANDROID_INCLUDE_HARDWARE_CONSUMERIR_H */
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