ota_esphome_inflate.h

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#pragma once
// Raw deflate decoder cut down from uzlib (https://github.com/pfalcon/uzlib,
// zlib licence, see the .c file); output goes through a ring window.
 
#include <stdbool.h>
#include <stdint.h>
 
#ifdef __cplusplus
extern "C" {
#endif
 
enum OtaInflateResult {
  OTA_INFLATE_OK = 0,   /* more data produced, call again */
  OTA_INFLATE_DONE = 1, /* end of compressed stream reached */
  OTA_INFLATE_DATA_ERROR = -3,
  OTA_INFLATE_DICT_ERROR = -5,
};
 
struct OtaInflateTree {
  uint16_t table[16]; /* table of code length counts */
  uint16_t *trans;    /* code -> symbol translation table, size entries */
  uint16_t size;
};
 
struct OtaInflateState {
  /* Next byte in the input buffer and one past its end */
  const unsigned char *source;
  const unsigned char *source_limit;
  /* Called when source is exhausted; returns the next byte or -1 at EOF.
     It may refill source/source_limit for buffered operation. */
  int (*source_read_cb)(struct OtaInflateState *d);
  /* Output cursor and one past the end of the output buffer */
  unsigned char *dest;
  unsigned char *dest_limit;
  /* Ring window holding the last dict_size output bytes for back references */
  unsigned char *dict_ring;
 
  unsigned int tag;
  unsigned int curlen;
  int lz_off;
  unsigned int dict_size;
  unsigned int dict_idx;
 
  /* One word: btype is -1 between blocks, bitcount never exceeds 7 */
  int8_t btype;
  uint8_t bfinal;
  uint8_t bitcount;
  bool eof;
 
  struct OtaInflateTree ltree; /* dynamic length/symbol tree */
  struct OtaInflateTree dtree; /* dynamic distance tree */
  uint16_t ltrans[288];
  uint16_t dtrans[32]; /* the distance alphabet has 30 symbols, so the tree is kept small */
};
 
/* dict must cover the encoder's window (its largest back reference) */
void ota_inflate_init(struct OtaInflateState *d, unsigned char *dict, unsigned int dict_len);
/* Fills dest up to dest_limit (OK) or to the end of the stream (DONE). dest may
   alias dict only if dest_limit - dest == dict_len and dest is reset to dict
   exactly when a call returns OK, so the ring index and dest stay in lockstep */
int ota_inflate(struct OtaInflateState *d);
 
#ifdef __cplusplus
}
#endif