text: /*
   * Copyright (c) 2006 Uwe Stuehler <uwe@openbsd.org>
   * Adaptations to ESP-IDF Copyright (c) 2016-2018 Espressif Systems (Shanghai) PTE LTD
   *
   * Permission to use, copy, modify, and distribute this software for any
   * purpose with or without fee is hereby granted, provided that the above
   * copyright notice and this permission notice appear in all copies.
   *
   * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
   * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
   * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
   * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
   * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
   * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
   */
  
  #include "sdmmc_common.h"
  #include "esp_attr.h"
  #include "esp_compiler.h"
  
  
  #define CIS_TUPLE(NAME)  (cis_tuple_t) {.code=CISTPL_CODE_##NAME, .name=#NAME, .func=&cis_tuple_func_default, }
  #define CIS_TUPLE_WITH_FUNC(NAME, FUNC)  (cis_tuple_t) {.code=CISTPL_CODE_##NAME, .name=#NAME, .func=&(FUNC), }
  
  #define CIS_CHECK_SIZE(SIZE, MINIMAL) do {int store_size = (SIZE); if((store_size) < (MINIMAL)) return ESP_ERR_INVALID_SIZE;} while(0)
  #define CIS_CHECK_UNSUPPORTED(COND) do {if(!(COND)) return ESP_ERR_NOT_SUPPORTED;} while(0)
  #define CIS_GET_MINIMAL_SIZE    32
  
  typedef esp_err_t (*cis_tuple_info_func_t)(const void* tuple_info, uint8_t* data, FILE* fp);
  
  typedef struct {
      int code;
      const char *name;
      cis_tuple_info_func_t   func;
  } cis_tuple_t;
  
  static const char* TAG = "sdmmc_io";
  
  static esp_err_t cis_tuple_func_default(const void* p, uint8_t* data, FILE* fp);
  static esp_err_t cis_tuple_func_manfid(const void* p, uint8_t* data, FILE* fp);
  static esp_err_t cis_tuple_func_cftable_entry(const void* p, uint8_t* data, FILE* fp);
  static esp_err_t cis_tuple_func_end(const void* p, uint8_t* data, FILE* fp);
  
  static const cis_tuple_t cis_table[] = {
      CIS_TUPLE(NULL),
      CIS_TUPLE(DEVICE),
      CIS_TUPLE(CHKSUM),
      CIS_TUPLE(VERS1),
      CIS_TUPLE(ALTSTR),
      CIS_TUPLE(CONFIG),
      CIS_TUPLE_WITH_FUNC(CFTABLE_ENTRY, cis_tuple_func_cftable_entry),
      CIS_TUPLE_WITH_FUNC(MANFID, cis_tuple_func_manfid),
      CIS_TUPLE(FUNCID),
      CIS_TUPLE(FUNCE),
      CIS_TUPLE(VENDER_BEGIN),
      CIS_TUPLE(VENDER_END),
      CIS_TUPLE(SDIO_STD),
      CIS_TUPLE(SDIO_EXT),
      CIS_TUPLE_WITH_FUNC(END, cis_tuple_func_end),
  };
  
  
  esp_err_t sdmmc_io_reset(sdmmc_card_t* card)
  {
      uint8_t sdio_reset = CCCR_CTL_RES;
      esp_err_t err = sdmmc_io_rw_direct(card, 0, SD_IO_CCCR_CTL, SD_ARG_CMD52_WRITE, &sdio_reset);
      if (err == ESP_ERR_TIMEOUT || (host_is_spi(card) && err == ESP_ERR_NOT_SUPPORTED)) {
          /* Non-IO cards are allowed to time out (in SD mode) or
           * return "invalid command" error (in SPI mode).
           */
      } else if (err == ESP_ERR_NOT_FOUND) {
          ESP_LOGD(TAG, "%s: card not present", __func__);
          return err;
      } else if (err != ESP_OK) {
          ESP_LOGE(TAG, "%s: unexpected return: 0x%x", __func__, err );
          return err;
      }
      return ESP_OK;
  }
  
  esp_err_t sdmmc_init_io(sdmmc_card_t* card)
  {
      /* IO_SEND_OP_COND(CMD5), Determine if the card is an IO card.
       * Non-IO cards will not respond to this command.
       */
      esp_err_t err = sdmmc_io_send_op_cond(card, 0, &card->ocr);
      if (err != ESP_OK) {
          ESP_LOGD(TAG, "%s: io_send_op_cond (1) returned 0x%x; not IO card", __func__, err);
          card->is_sdio = 0;
          card->is_mem = 1;
      } else {
          card->is_sdio = 1;
  
          if (card->ocr & SD_IO_OCR_MEM_PRESENT) {
              ESP_LOGD(TAG, "%s: IO-only card", __func__);
              card->is_mem = 0;
          }
          card->num_io_functions = SD_IO_OCR_NUM_FUNCTIONS(card->ocr);
          ESP_LOGD(TAG, "%s: number of IO functions: %d", __func__, card->num_io_functions);
          if (card->num_io_functions == 0) {
              card->is_sdio = 0;
          }
          uint32_t host_ocr = get_host_ocr(card->host.io_voltage);
          host_ocr &= card->ocr;
          err = sdmmc_io_send_op_cond(card, host_ocr, &card->ocr);
          if (err != ESP_OK) {
              ESP_LOGE(TAG, "%s: sdmmc_io_send_op_cond (1) returned 0x%x", __func__, err);
              return err;
          }
          err = sdmmc_io_enable_int(card);
          if (err != ESP_OK) {
              ESP_LOGD(TAG, "%s: sdmmc_enable_int failed (0x%x)", __func__, err);
          }
      }
      return ESP_OK;
  }
  
  esp_err_t sdmmc_init_io_bus_width(sdmmc_card_t* card)
  {
      esp_err_t err;
      card->log_bus_width = 0;
      if (card->host.flags & SDMMC_HOST_FLAG_4BIT) {
          uint8_t card_cap = 0;
          err = sdmmc_io_rw_direct(card, 0, SD_IO_CCCR_CARD_CAP,
                  SD_ARG_CMD52_READ, &card_cap);
          if (err != ESP_OK) {
              ESP_LOGE(TAG, "%s: sdmmc_io_rw_direct (read SD_IO_CCCR_CARD_CAP) returned 0x%0x", __func__, err);
              return err;
          }
          ESP_LOGD(TAG, "IO card capabilities byte: %02x", card_cap);
          if (!(card_cap & CCCR_CARD_CAP_LSC) ||
                  (card_cap & CCCR_CARD_CAP_4BLS)) {
              // This card supports 4-bit bus mode
              uint8_t bus_width = CCCR_BUS_WIDTH_4;
              err = sdmmc_io_rw_direct(card, 0, SD_IO_CCCR_BUS_WIDTH,
                                  SD_ARG_CMD52_WRITE, &bus_width);
              if (err != ESP_OK) {
                  ESP_LOGE(TAG, "%s: sdmmc_io_rw_direct (write SD_IO_CCCR_BUS_WIDTH) returned 0x%0x", __func__, err);
                  return err;
              }
              card->log_bus_width = 2;
          }
      }
      return ESP_OK;
  }
  
  
  esp_err_t sdmmc_io_enable_hs_mode(sdmmc_card_t* card)
  {
      /* If the host is configured to use low frequency, don't attempt to switch */
      if (card->host.max_freq_khz < SDMMC_FREQ_DEFAULT) {
          card->max_freq_khz = card->host.max_freq_khz;
          return ESP_OK;
      } else if (card->host.max_freq_khz < SDMMC_FREQ_HIGHSPEED) {
          card->max_freq_khz = SDMMC_FREQ_DEFAULT;
          return ESP_OK;
      }
  
      /* For IO cards, do write + read operation on "High Speed" register,
       * setting EHS bit. If both EHS and SHS read back as set, then HS mode
       * has been enabled.
       */
      uint8_t val = CCCR_HIGHSPEED_ENABLE;
      esp_err_t err = sdmmc_io_rw_direct(card, 0, SD_IO_CCCR_HIGHSPEED,
              SD_ARG_CMD52_WRITE | SD_ARG_CMD52_EXCHANGE, &val);
      if (err != ESP_OK) {
          ESP_LOGD(TAG, "%s: sdmmc_io_rw_direct returned 0x%x", __func__, err);
          return err;
      }
  
      ESP_LOGD(TAG, "%s: CCCR_HIGHSPEED=0x%02x", __func__, val);
      const uint8_t hs_mask = CCCR_HIGHSPEED_ENABLE | CCCR_HIGHSPEED_SUPPORT;
      if ((val & hs_mask) != hs_mask) {
          return ESP_ERR_NOT_SUPPORTED;
      }
      card->max_freq_khz = SDMMC_FREQ_HIGHSPEED;
      return ESP_OK;
  }
  
  
  esp_err_t sdmmc_io_send_op_cond(sdmmc_card_t* card, uint32_t ocr, uint32_t *ocrp)
  {
      esp_err_t err = ESP_OK;
      sdmmc_command_t cmd = {
          .flags = SCF_CMD_BCR | SCF_RSP_R4,
          .arg = ocr,
          .opcode = SD_IO_SEND_OP_COND
      };
      for (size_t i = 0; i < 100; i++) {
          err = sdmmc_send_cmd(card, &cmd);
          if (err != ESP_OK) {
              break;
          }
          if ((MMC_R4(cmd.response) & SD_IO_OCR_MEM_READY) ||
              ocr == 0) {
              break;
          }
          err = ESP_ERR_TIMEOUT;
          vTaskDelay(SDMMC_IO_SEND_OP_COND_DELAY_MS / portTICK_PERIOD_MS);
      }
      if (err == ESP_OK && ocrp != NULL)
          *ocrp = MMC_R4(cmd.response);
  
      return err;
  }
  
  esp_err_t sdmmc_io_rw_direct(sdmmc_card_t* card, int func,
          uint32_t reg, uint32_t arg, uint8_t *byte)
  {
      esp_err_t err;
      sdmmc_command_t cmd = {
          .flags = SCF_CMD_AC | SCF_RSP_R5,
          .arg = 0,
          .opcode = SD_IO_RW_DIRECT
      };
  
      arg |= (func & SD_ARG_CMD52_FUNC_MASK) << SD_ARG_CMD52_FUNC_SHIFT;
      arg |= (reg & SD_ARG_CMD52_REG_MASK) << SD_ARG_CMD52_REG_SHIFT;
      arg |= (*byte & SD_ARG_CMD52_DATA_MASK) << SD_ARG_CMD52_DATA_SHIFT;
      cmd.arg = arg;
  
      err = sdmmc_send_cmd(card, &cmd);
      if (err != ESP_OK) {
          ESP_LOGV(TAG, "%s: sdmmc_send_cmd returned 0x%x", __func__, err);
          return err;
      }
  
      *byte = SD_R5_DATA(cmd.response);
  
      return ESP_OK;
  }
  
  
  esp_err_t sdmmc_io_read_byte(sdmmc_card_t* card, uint32_t function,
          uint32_t addr, uint8_t *out_byte)
  {
      esp_err_t ret = sdmmc_io_rw_direct(card, function, addr, SD_ARG_CMD52_READ, out_byte);
      if (unlikely(ret != ESP_OK)) {
          ESP_LOGE(TAG, "%s: sdmmc_io_rw_direct (read 0x%x) returned 0x%x", __func__, addr, ret);
      }
      return ret;
  }
  
  esp_err_t sdmmc_io_write_byte(sdmmc_card_t* card, uint32_t function,
          uint32_t addr, uint8_t in_byte, uint8_t* out_byte)
  {
      uint8_t tmp_byte = in_byte;
      esp_err_t ret = sdmmc_io_rw_direct(card, function, addr,
              SD_ARG_CMD52_WRITE | SD_ARG_CMD52_EXCHANGE, &tmp_byte);
      if (unlikely(ret != ESP_OK)) {
          ESP_LOGE(TAG, "%s: sdmmc_io_rw_direct (write 0x%x) returned 0x%x", __func__, addr, ret);
          return ret;
      }
      if (out_byte != NULL) {
          *out_byte = tmp_byte;
      }
      return ESP_OK;
  }
  
  esp_err_t sdmmc_io_rw_extended(sdmmc_card_t* card, int func,
      uint32_t reg, int arg, void *datap, size_t datalen)
  {
      esp_err_t err;
      const size_t max_byte_transfer_size = 512;
      sdmmc_command_t cmd = {
          .flags = SCF_CMD_AC | SCF_RSP_R5,
          .arg = 0,
          .opcode = SD_IO_RW_EXTENDED,
          .data = datap,
          .datalen = datalen,
          .blklen = max_byte_transfer_size /* TODO: read max block size from CIS */
      };
  
      uint32_t count; /* number of bytes or blocks, depending on transfer mode */
      if (arg & SD_ARG_CMD53_BLOCK_MODE) {
          if (cmd.datalen % cmd.blklen != 0) {
              return ESP_ERR_INVALID_SIZE;
          }
          count = cmd.datalen / cmd.blklen;
      } else {
          if (datalen > max_byte_transfer_size) {
              /* TODO: split into multiple operations? */
              return ESP_ERR_INVALID_SIZE;
          }
          if (datalen == max_byte_transfer_size) {
              count = 0;  // See 5.3.1 SDIO simplifed spec
          } else {
              count = datalen;
          }
          cmd.blklen = datalen;
      }
  
      arg |= (func & SD_ARG_CMD53_FUNC_MASK) << SD_ARG_CMD53_FUNC_SHIFT;
      arg |= (reg & SD_ARG_CMD53_REG_MASK) << SD_ARG_CMD53_REG_SHIFT;
      arg |= (count & SD_ARG_CMD53_LENGTH_MASK) << SD_ARG_CMD53_LENGTH_SHIFT;
      cmd.arg = arg;
  
      if ((arg & SD_ARG_CMD53_WRITE) == 0) {
          cmd.flags |= SCF_CMD_READ;
      }
  
      err = sdmmc_send_cmd(card, &cmd);
      if (err != ESP_OK) {
          ESP_LOGE(TAG, "%s: sdmmc_send_cmd returned 0x%x", __func__, err);
          return err;
      }
  
      return ESP_OK;
  }
  
  esp_err_t sdmmc_io_read_bytes(sdmmc_card_t* card, uint32_t function,
          uint32_t addr, void* dst, size_t size)
  {
      /* host quirk: SDIO transfer with length not divisible by 4 bytes
       * has to be split into two transfers: one with aligned length,
       * the other one for the remaining 1-3 bytes.
       */
      uint8_t *pc_dst = dst;
      while (size > 0) {
          size_t size_aligned = size & (~3);
          size_t will_transfer = size_aligned > 0 ? size_aligned : size;
  
          esp_err_t err = sdmmc_io_rw_extended(card, function, addr,
                  SD_ARG_CMD53_READ | SD_ARG_CMD53_INCREMENT,
                  pc_dst, will_transfer);
          if (unlikely(err != ESP_OK)) {
              return err;
          }
          pc_dst += will_transfer;
          size -= will_transfer;
          addr += will_transfer;
      }
      return ESP_OK;
  }
  
  esp_err_t sdmmc_io_write_bytes(sdmmc_card_t* card, uint32_t function,
          uint32_t addr, const void* src, size_t size)
  {
      /* same host quirk as in sdmmc_io_read_bytes */
      const uint8_t *pc_src = (const uint8_t*) src;
  
      while (size > 0) {
          size_t size_aligned = size & (~3);
          size_t will_transfer = size_aligned > 0 ? size_aligned : size;
  
          esp_err_t err = sdmmc_io_rw_extended(card, function, addr,
                  SD_ARG_CMD53_WRITE | SD_ARG_CMD53_INCREMENT,
                  (void*) pc_src, will_transfer);
          if (unlikely(err != ESP_OK)) {
              return err;
          }
          pc_src += will_transfer;
          size -= will_transfer;
          addr += will_transfer;
      }
      return ESP_OK;
  }
  
  esp_err_t sdmmc_io_read_blocks(sdmmc_card_t* card, uint32_t function,
          uint32_t addr, void* dst, size_t size)
  {
      if (unlikely(size % 4 != 0)) {
          return ESP_ERR_INVALID_SIZE;
      }
      return sdmmc_io_rw_extended(card, function, addr,
              SD_ARG_CMD53_READ | SD_ARG_CMD53_INCREMENT | SD_ARG_CMD53_BLOCK_MODE,
              dst, size);
  }
  
  esp_err_t sdmmc_io_write_blocks(sdmmc_card_t* card, uint32_t function,
          uint32_t addr, const void* src, size_t size)
  {
      if (unlikely(size % 4 != 0)) {
          return ESP_ERR_INVALID_SIZE;
      }
      return sdmmc_io_rw_extended(card, function, addr,
              SD_ARG_CMD53_WRITE | SD_ARG_CMD53_INCREMENT | SD_ARG_CMD53_BLOCK_MODE,
              (void*) src, size);
  }
  
  esp_err_t sdmmc_io_enable_int(sdmmc_card_t* card)
  {
      if (card->host.io_int_enable == NULL) {
          return ESP_ERR_NOT_SUPPORTED;
      }
      return (*card->host.io_int_enable)(card->host.slot);
  }
  
  esp_err_t sdmmc_io_wait_int(sdmmc_card_t* card, TickType_t timeout_ticks)
  {
      if (card->host.io_int_wait == NULL) {
          return ESP_ERR_NOT_SUPPORTED;
      }
      return (*card->host.io_int_wait)(card->host.slot, timeout_ticks);
  }
  
  
  /*
   * Print the CIS information of a CIS card, currently only ESP slave supported.
   */
  
  static esp_err_t cis_tuple_func_default(const void* p, uint8_t* data, FILE* fp)
  {
      const cis_tuple_t* tuple = (const cis_tuple_t*)p;
      uint8_t code = *(data++);
      int size = *(data++);
      if (tuple) {
          fprintf(fp, "TUPLE: %s, size: %d: ", tuple->name, size);
      } else {
          fprintf(fp, "TUPLE: unknown(%02X), size: %d: ", code, size);
      }
      for (int i = 0; i < size; i++) fprintf(fp, "%02X ", *(data++));
      fprintf(fp, "\n");
      return ESP_OK;
  }
  
  static esp_err_t cis_tuple_func_manfid(const void* p, uint8_t* data, FILE* fp)
  {
      const cis_tuple_t* tuple = (const cis_tuple_t*)p;
      data++;
      int size = *(data++);
      fprintf(fp, "TUPLE: %s, size: %d\n", tuple->name, size);
      CIS_CHECK_SIZE(size, 4);
      fprintf(fp, "  MANF: %04X, CARD: %04X\n", *(uint16_t*)(data), *(uint16_t*)(data+2));
      return ESP_OK;
  }
  
  static esp_err_t cis_tuple_func_end(const void* p, uint8_t* data, FILE* fp)
  {
      const cis_tuple_t* tuple = (const cis_tuple_t*)p;
      data++;
      fprintf(fp, "TUPLE: %s\n", tuple->name);
      return ESP_OK;
  }
  
  static esp_err_t cis_tuple_func_cftable_entry(const void* p, uint8_t* data, FILE* fp)
  {
      const cis_tuple_t* tuple = (const cis_tuple_t*)p;
      data++;
      int size = *(data++);
      fprintf(fp, "TUPLE: %s, size: %d\n", tuple->name, size);
      CIS_CHECK_SIZE(size, 2);
  
      CIS_CHECK_SIZE(size--, 1);
      bool interface = data[0] & BIT(7);
      bool def = data[0] & BIT(6);
      int conf_ent_num = data[0] & 0x3F;
      fprintf(fp, "  INDX: %02X, Intface: %d, Default: %d, Conf-Entry-Num: %d\n", *(data++), interface, def, conf_ent_num);
  
      if (interface) {
          CIS_CHECK_SIZE(size--, 1);
          fprintf(fp, "  IF: %02X\n", *(data++));
      }
  
      CIS_CHECK_SIZE(size--, 1);
      bool misc = data[0] & BIT(7);
      int mem_space = (data[0] >> 5 )&(0x3);
      bool irq = data[0] & BIT(4);
      bool io_sp = data[0] & BIT(3);
      bool timing = data[0] & BIT(2);
      int power = data[0] & 3;
      fprintf(fp, "  FS: %02X, misc: %d, mem_space: %d, irq: %d, io_space: %d, timing: %d, power: %d\n", *(data++), misc, mem_space, irq, io_sp, timing, power);
  
      CIS_CHECK_UNSUPPORTED(power == 0);  //power descriptor is not handled yet
      CIS_CHECK_UNSUPPORTED(!timing);     //timing descriptor is not handled yet
      CIS_CHECK_UNSUPPORTED(!io_sp);      //io space descriptor is not handled yet
  
      if (irq) {
          CIS_CHECK_SIZE(size--, 1);
          bool mask = data[0] & BIT(4);
          fprintf(fp, "  IR: %02X, mask: %d, ",*(data++), mask);
          if (mask) {
              CIS_CHECK_SIZE(size, 2);
              size-=2;
              fprintf(fp, "  IRQ: %02X %02X\n", data[0], data[1]);
              data+=2;
          }
      }
  
      if (mem_space) {
          CIS_CHECK_SIZE(size, 2);
          size-=2;
          CIS_CHECK_UNSUPPORTED(mem_space==1); //other cases not handled yet
          int len = *(uint16_t*)data;
          fprintf(fp, "  LEN: %04X\n", len);
          data+=2;
      }
  
      CIS_CHECK_UNSUPPORTED(misc==0);    //misc descriptor is not handled yet
      return ESP_OK;
  }
  
  static const cis_tuple_t* get_tuple(uint8_t code)
  {
      for (int i = 0; i < sizeof(cis_table)/sizeof(cis_tuple_t); i++) {
          if (code == cis_table[i].code) return &cis_table[i];
      }
      return NULL;
  }
  
  esp_err_t sdmmc_io_print_cis_info(uint8_t* buffer, size_t buffer_size, FILE* fp)
  {
      ESP_LOG_BUFFER_HEXDUMP("CIS", buffer, buffer_size, ESP_LOG_DEBUG);
      if (!fp) fp = stdout;
  
      uint8_t* cis = buffer;
      do {
          const cis_tuple_t* tuple = get_tuple(cis[0]);
          int size = cis[1];
          esp_err_t ret = ESP_OK;
          if (tuple) {
              ret = tuple->func(tuple, cis, fp);
          } else {
              ret = cis_tuple_func_default(NULL, cis, fp);
          }
          if (ret != ESP_OK) return ret;
          cis += 2 + size;
          if (tuple && tuple->code == CISTPL_CODE_END) break;
      } while (cis < buffer + buffer_size) ;
      return ESP_OK;
  }
  
  /**
   * Check tuples in the buffer.
   *
   * @param buf Buffer to check
   * @param buffer_size Size of the buffer
   * @param inout_cis_offset
   *          - input: the last cis_offset, relative to the beginning of the buf. -1 if
   *                      this buffer begin with the tuple length, otherwise should be no smaller than
   *                      zero.
   *          - output: when the end tuple found, output offset of the CISTPL_CODE_END
   *                      byte + 1 (relative to the beginning of the buffer; when not found, output
   *                      the address of next tuple code.
   *
   * @return true if found, false if haven't.
   */
  static bool check_tuples_in_buffer(uint8_t* buf, int buffer_size, int* inout_cis_offset)
  {
      int cis_offset = *inout_cis_offset;
      if (cis_offset == -1) {
          //the CIS code is checked in the last buffer, skip to next tuple
          cis_offset += buf[0] + 2;
      }
      assert(cis_offset >= 0);
      while (1) {
          if (cis_offset < buffer_size) {
              //A CIS code in the buffer, check it
              if (buf[cis_offset] == CISTPL_CODE_END) {
                  *inout_cis_offset = cis_offset + 1;
                  return true;
              }
          }
          if (cis_offset + 1 < buffer_size) {
              cis_offset += buf[cis_offset+1] + 2;
          } else {
              break;
          }
      }
      *inout_cis_offset = cis_offset;
      return false;
  }
  
  esp_err_t sdmmc_io_get_cis_data(sdmmc_card_t* card, uint8_t* out_buffer, size_t buffer_size, size_t* inout_cis_size)
  {
      esp_err_t ret = ESP_OK;
      WORD_ALIGNED_ATTR uint8_t buf[CIS_GET_MINIMAL_SIZE];
  
      /*
       * CIS region exist in 0x1000~0x17FFF of FUNC 0, get the start address of it
       * from CCCR register.
       */
      uint32_t addr;
      ret = sdmmc_io_read_bytes(card, 0, 9, &addr, 3);
      if (ret != ESP_OK) return ret;
      //the sdmmc_io driver reads 4 bytes, the most significant byte is not the address.
      addr &= 0xffffff;
      if (addr < 0x1000 || addr > 0x17FFF) {
          return ESP_ERR_INVALID_RESPONSE;
      }
  
      /*
       * To avoid reading too long, take the input value as limitation if
       * existing.
       */
      size_t max_reading = UINT32_MAX;
      if (inout_cis_size && *inout_cis_size != 0) {
          max_reading = *inout_cis_size;
      }
  
      /*
       * Parse the length while reading. If find the end tuple, or reaches the
       * limitation, read no more and return both the data and the size already
       * read.
       */
      int buffer_offset = 0;
      int cur_cis_offset = 0;
      bool end_tuple_found = false;
      do {
          ret = sdmmc_io_read_bytes(card, 0, addr + buffer_offset, &buf, CIS_GET_MINIMAL_SIZE);
          if (ret != ESP_OK) return ret;
  
          //calculate relative to the beginning of the buffer
          int offset = cur_cis_offset - buffer_offset;
          bool finish = check_tuples_in_buffer(buf, CIS_GET_MINIMAL_SIZE, &offset);
  
          int remain_size = buffer_size - buffer_offset;
          int copy_len;
          if (finish) {
              copy_len = MIN(offset, remain_size);
              end_tuple_found = true;
          } else {
              copy_len = MIN(CIS_GET_MINIMAL_SIZE, remain_size);
          }
          if (copy_len > 0) {
              memcpy(out_buffer + buffer_offset, buf, copy_len);
          }
          cur_cis_offset = buffer_offset + offset;
          buffer_offset += CIS_GET_MINIMAL_SIZE;
      } while (!end_tuple_found && buffer_offset < max_reading);
  
      if (end_tuple_found) {
          *inout_cis_size = cur_cis_offset;
          if (cur_cis_offset > buffer_size) {
              return ESP_ERR_INVALID_SIZE;
          } else {
              return ESP_OK;
          }
      } else {
          return ESP_ERR_NOT_FOUND;
      }
  }
  