linux-zen-desktop/drivers/media/platform/allegro-dvt/nal-rbsp.c

311 lines
5.7 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2019-2020 Pengutronix, Michael Tretter <kernel@pengutronix.de>
*
* Helper functions to generate a raw byte sequence payload from values.
*/
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/v4l2-controls.h>
#include <linux/device.h>
#include <linux/export.h>
#include <linux/log2.h>
#include "nal-rbsp.h"
void rbsp_init(struct rbsp *rbsp, void *addr, size_t size,
struct nal_rbsp_ops *ops)
{
if (!rbsp)
return;
rbsp->data = addr;
rbsp->size = size;
rbsp->pos = 0;
rbsp->ops = ops;
rbsp->error = 0;
}
void rbsp_unsupported(struct rbsp *rbsp)
{
rbsp->error = -EINVAL;
}
static int rbsp_read_bits(struct rbsp *rbsp, int n, unsigned int *value);
static int rbsp_write_bits(struct rbsp *rbsp, int n, unsigned int value);
/*
* When reading or writing, the emulation_prevention_three_byte is detected
* only when the 2 one bits need to be inserted. Therefore, we are not
* actually adding the 0x3 byte, but the 2 one bits and the six 0 bits of the
* next byte.
*/
#define EMULATION_PREVENTION_THREE_BYTE (0x3 << 6)
static int add_emulation_prevention_three_byte(struct rbsp *rbsp)
{
rbsp->num_consecutive_zeros = 0;
rbsp_write_bits(rbsp, 8, EMULATION_PREVENTION_THREE_BYTE);
return 0;
}
static int discard_emulation_prevention_three_byte(struct rbsp *rbsp)
{
unsigned int tmp = 0;
rbsp->num_consecutive_zeros = 0;
rbsp_read_bits(rbsp, 8, &tmp);
if (tmp != EMULATION_PREVENTION_THREE_BYTE)
return -EINVAL;
return 0;
}
static inline int rbsp_read_bit(struct rbsp *rbsp)
{
int shift;
int ofs;
int bit;
int err;
if (rbsp->num_consecutive_zeros == 22) {
err = discard_emulation_prevention_three_byte(rbsp);
if (err)
return err;
}
shift = 7 - (rbsp->pos % 8);
ofs = rbsp->pos / 8;
if (ofs >= rbsp->size)
return -EINVAL;
bit = (rbsp->data[ofs] >> shift) & 1;
rbsp->pos++;
if (bit == 1 ||
(rbsp->num_consecutive_zeros < 7 && (rbsp->pos % 8 == 0)))
rbsp->num_consecutive_zeros = 0;
else
rbsp->num_consecutive_zeros++;
return bit;
}
static inline int rbsp_write_bit(struct rbsp *rbsp, bool value)
{
int shift;
int ofs;
if (rbsp->num_consecutive_zeros == 22)
add_emulation_prevention_three_byte(rbsp);
shift = 7 - (rbsp->pos % 8);
ofs = rbsp->pos / 8;
if (ofs >= rbsp->size)
return -EINVAL;
rbsp->data[ofs] &= ~(1 << shift);
rbsp->data[ofs] |= value << shift;
rbsp->pos++;
if (value ||
(rbsp->num_consecutive_zeros < 7 && (rbsp->pos % 8 == 0))) {
rbsp->num_consecutive_zeros = 0;
} else {
rbsp->num_consecutive_zeros++;
}
return 0;
}
static inline int rbsp_read_bits(struct rbsp *rbsp, int n, unsigned int *value)
{
int i;
int bit;
unsigned int tmp = 0;
if (n > 8 * sizeof(*value))
return -EINVAL;
for (i = n; i > 0; i--) {
bit = rbsp_read_bit(rbsp);
if (bit < 0)
return bit;
tmp |= bit << (i - 1);
}
if (value)
*value = tmp;
return 0;
}
static int rbsp_write_bits(struct rbsp *rbsp, int n, unsigned int value)
{
int ret;
if (n > 8 * sizeof(value))
return -EINVAL;
while (n--) {
ret = rbsp_write_bit(rbsp, (value >> n) & 1);
if (ret)
return ret;
}
return 0;
}
static int rbsp_read_uev(struct rbsp *rbsp, unsigned int *value)
{
int leading_zero_bits = 0;
unsigned int tmp = 0;
int ret;
while ((ret = rbsp_read_bit(rbsp)) == 0)
leading_zero_bits++;
if (ret < 0)
return ret;
if (leading_zero_bits > 0) {
ret = rbsp_read_bits(rbsp, leading_zero_bits, &tmp);
if (ret)
return ret;
}
if (value)
*value = (1 << leading_zero_bits) - 1 + tmp;
return 0;
}
static int rbsp_write_uev(struct rbsp *rbsp, unsigned int *value)
{
int ret;
int leading_zero_bits;
if (!value)
return -EINVAL;
leading_zero_bits = ilog2(*value + 1);
ret = rbsp_write_bits(rbsp, leading_zero_bits, 0);
if (ret)
return ret;
return rbsp_write_bits(rbsp, leading_zero_bits + 1, *value + 1);
}
static int rbsp_read_sev(struct rbsp *rbsp, int *value)
{
int ret;
unsigned int tmp;
ret = rbsp_read_uev(rbsp, &tmp);
if (ret)
return ret;
if (value) {
if (tmp & 1)
*value = (tmp + 1) / 2;
else
*value = -(tmp / 2);
}
return 0;
}
static int rbsp_write_sev(struct rbsp *rbsp, int *value)
{
unsigned int tmp;
if (!value)
return -EINVAL;
if (*value > 0)
tmp = (2 * (*value)) | 1;
else
tmp = -2 * (*value);
return rbsp_write_uev(rbsp, &tmp);
}
static int __rbsp_write_bit(struct rbsp *rbsp, int *value)
{
return rbsp_write_bit(rbsp, *value);
}
static int __rbsp_write_bits(struct rbsp *rbsp, int n, unsigned int *value)
{
return rbsp_write_bits(rbsp, n, *value);
}
struct nal_rbsp_ops write = {
.rbsp_bit = __rbsp_write_bit,
.rbsp_bits = __rbsp_write_bits,
.rbsp_uev = rbsp_write_uev,
.rbsp_sev = rbsp_write_sev,
};
static int __rbsp_read_bit(struct rbsp *rbsp, int *value)
{
int tmp = rbsp_read_bit(rbsp);
if (tmp < 0)
return tmp;
*value = tmp;
return 0;
}
struct nal_rbsp_ops read = {
.rbsp_bit = __rbsp_read_bit,
.rbsp_bits = rbsp_read_bits,
.rbsp_uev = rbsp_read_uev,
.rbsp_sev = rbsp_read_sev,
};
void rbsp_bit(struct rbsp *rbsp, int *value)
{
if (rbsp->error)
return;
rbsp->error = rbsp->ops->rbsp_bit(rbsp, value);
}
void rbsp_bits(struct rbsp *rbsp, int n, int *value)
{
if (rbsp->error)
return;
rbsp->error = rbsp->ops->rbsp_bits(rbsp, n, value);
}
void rbsp_uev(struct rbsp *rbsp, unsigned int *value)
{
if (rbsp->error)
return;
rbsp->error = rbsp->ops->rbsp_uev(rbsp, value);
}
void rbsp_sev(struct rbsp *rbsp, int *value)
{
if (rbsp->error)
return;
rbsp->error = rbsp->ops->rbsp_sev(rbsp, value);
}
void rbsp_trailing_bits(struct rbsp *rbsp)
{
unsigned int rbsp_stop_one_bit = 1;
unsigned int rbsp_alignment_zero_bit = 0;
rbsp_bit(rbsp, &rbsp_stop_one_bit);
rbsp_bits(rbsp, round_up(rbsp->pos, 8) - rbsp->pos,
&rbsp_alignment_zero_bit);
}