Generate Code to Read a Text File

% y = readfile(filename)
% Read file 'filename' and return a MATLAB string with the contents
% of the file.
function y = readfile(filename) %#codegen

% Put class and size constraints on function input.
assert(isa(filename, 'char'));
assert(size(filename, 1) == 1);
assert(size(filename, 2) <= 1024);

% Call fopen(filename 'r'), but we need to convert the MATLAB
% string into a C type string (which is the same string with the
% NUL (\0) string terminator).
f = fopen(filename, 'r');

% Call fseek(f, 0, SEEK_END) to set file position to the end of
% the file.
fseek(f, 0, 'eof');

% Call ftell(f) which will return the length of the file in bytes
% (as current file position is at the end of the file).
filelen = int32(ftell(f));

% Reset current file position
fseek(f,0,'bof');

% Initialize a buffer
maxBufferSize = int32(2^16);
buffer = zeros(1, maxBufferSize,'uint8');

% Remaining is the number of bytes to read (from the file)
remaining = filelen;

% Index is the current position to read into the buffer
index = int32(1);

while remaining > 0
    % Buffer overflow?
    if remaining + index > size(buffer,2)
        fprintf('Attempt to read file which is bigger than internal buffer.\n');
        fprintf('Current buffer size is %d bytes and file size is %d bytes.\n', maxBufferSize, filelen);
        break
    end
    % Read as much as possible from the file into internal buffer

    [dataRead, nread] = fread(f,remaining, 'char');
    buffer(index:index+nread-1) = dataRead;
    n = int32(nread);
    if n == 0
        % Nothing more to read
        break;
    end
    % Did something went wrong when reading?
    if n < 0
        fprintf('Could not read from file: %d.\n', n);
        break;
    end
    % Update state variables
    remaining = remaining - n;
    index = index + n;
end

% Close file
fclose(f);

y = char(buffer(1:index));

Code generation successful.

ans = 1×2

           1        1857

ans = 
    '% y = readfile(filename)
     % Read file 'filename' and return a MATLAB string with the contents
     % of th'

Code generation successful.

.                      ..                     _clang-format          buildInfo.mat          codeInfo.mat           codedescriptor.dmr     compileInfo.mat        examples               fileManager.c          fileManager.h          fileManager.o          fread.c                fread.h                fread.o                fseek.c                fseek.h                fseek.o                ftell.c                ftell.h                ftell.o                interface              readfile.a             readfile.c             readfile.h             readfile.o             readfile_data.c        readfile_data.h        readfile_data.o        readfile_emxAPI.c      readfile_emxAPI.h      readfile_emxAPI.o      readfile_emxutil.c     readfile_emxutil.h     readfile_emxutil.o     readfile_initialize.c  readfile_initialize.h  readfile_initialize.o  readfile_rtw.mk        readfile_terminate.c   readfile_terminate.h   readfile_terminate.o   readfile_types.h       rtw_proj.tmw           rtwtypes.h             

/*
 * File: readfile.c
 *
 * MATLAB Coder version            : 24.2
 * C/C++ source code generated on  : 05-Sep-2024 13:46:24
 */

/* Include Files */
#include "readfile.h"
#include "fileManager.h"
#include "fread.h"
#include "fseek.h"
#include "ftell.h"
#include "readfile_data.h"
#include "readfile_emxutil.h"
#include "readfile_initialize.h"
#include "readfile_types.h"
#include <math.h>
#include <stdio.h>
#include <string.h>

/* Function Declarations */
static double rt_roundd_snf(double u);

/* Function Definitions */
/*
 * Arguments    : double u
 * Return Type  : double
 */
static double rt_roundd_snf(double u)
{
  double y;
  if (fabs(u) < 4.503599627370496E+15) {
    if (u >= 0.5) {
      y = floor(u + 0.5);
    } else if (u > -0.5) {
      y = u * 0.0;
    } else {
      y = ceil(u - 0.5);
    }
  } else {
    y = u;
  }
  return y;
}

/*
 * Put class and size constraints on function input.
 *
 * Arguments    : const char filename_data[]
 *                const int filename_size[2]
 *                emxArray_char_T *y
 * Return Type  : void
 */
void readfile(const char filename_data[], const int filename_size[2],
              emxArray_char_T *y)
{
  emxArray_real_T *dataRead;
  double d;
  double *dataRead_data;
  int b_index;
  int i;
  int i2;
  int remaining;
  unsigned char buffer[65536];
  signed char fileid;
  char *y_data;
  boolean_T exitg1;
  if (!isInitialized_readfile) {
    readfile_initialize();
  }
  /*  y = readfile(filename) */
  /*  Read file 'filename' and return a MATLAB string with the contents */
  /*  of the file. */
  /*  Call fopen(filename 'r'), but we need to convert the MATLAB */
  /*  string into a C type string (which is the same string with the */
  /*  NUL (\0) string terminator). */
  fileid = cfopen(filename_data, filename_size);
  /*  Call fseek(f, 0, SEEK_END) to set file position to the end of */
  /*  the file. */
  b_fseek(fileid);
  /*  Call ftell(f) which will return the length of the file in bytes */
  /*  (as current file position is at the end of the file). */
  d = rt_roundd_snf(b_ftell(fileid));
  if (d < 2.147483648E+9) {
    if (d >= -2.147483648E+9) {
      i = (int)d;
    } else {
      i = MIN_int32_T;
    }
  } else if (d >= 2.147483648E+9) {
    i = MAX_int32_T;
  } else {
    i = 0;
  }
  /*  Reset current file position */
  c_fseek(fileid);
  /*  Initialize a buffer */
  memset(&buffer[0], 0, 65536U * sizeof(unsigned char));
  /*  Remaining is the number of bytes to read (from the file) */
  remaining = i;
  /*  Index is the current position to read into the buffer */
  b_index = 1;
  emxInit_real_T(&dataRead);
  exitg1 = false;
  while ((!exitg1) && (remaining > 0)) {
    int qY;
    /*  Buffer overflow? */
    if (b_index > MAX_int32_T - remaining) {
      qY = MAX_int32_T;
    } else {
      qY = remaining + b_index;
    }
    if (qY > 65536) {
      printf("Attempt to read file which is bigger than internal buffer.\n");
      fflush(stdout);
      printf("Current buffer size is %d bytes and file size is %d bytes.\n",
             65536, i);
      fflush(stdout);
      exitg1 = true;
    } else {
      double nread;
      int i1;
      /*  Read as much as possible from the file into internal buffer */
      nread = b_fread(fileid, remaining, dataRead);
      dataRead_data = dataRead->data;
      d = rt_roundd_snf((double)b_index + nread);
      if (d < 2.147483648E+9) {
        if (d >= -2.147483648E+9) {
          qY = (int)d;
        } else {
          qY = MIN_int32_T;
        }
      } else if (d >= 2.147483648E+9) {
        qY = MAX_int32_T;
      } else {
        qY = 0;
      }
      if (qY < -2147483647) {
        qY = MIN_int32_T;
      } else {
        qY--;
      }
      if (b_index > qY) {
        i1 = 0;
        qY = 0;
      } else {
        i1 = b_index - 1;
      }
      qY -= i1;
      for (i2 = 0; i2 < qY; i2++) {
        unsigned char u;
        d = rt_roundd_snf(dataRead_data[i2]);
        if (d < 256.0) {
          if (d >= 0.0) {
            u = (unsigned char)d;
          } else {
            u = 0U;
          }
        } else if (d >= 256.0) {
          u = MAX_uint8_T;
        } else {
          u = 0U;
        }
        buffer[i1 + i2] = u;
      }
      d = rt_roundd_snf(nread);
      if (d < 2.147483648E+9) {
        if (d >= -2.147483648E+9) {
          qY = (int)d;
        } else {
          qY = MIN_int32_T;
        }
      } else if (d >= 2.147483648E+9) {
        qY = MAX_int32_T;
      } else {
        qY = 0;
      }
      if (qY == 0) {
        /*  Nothing more to read */
        exitg1 = true;

        /*  Did something went wrong when reading? */
      } else if (qY < 0) {
        printf("Could not read from file: %d.\n", qY);
        fflush(stdout);
        exitg1 = true;
      } else {
        /*  Update state variables */
        remaining -= qY;
        if ((b_index < 0) && (qY < MIN_int32_T - b_index)) {
          b_index = MIN_int32_T;
        } else if ((b_index > 0) && (qY > MAX_int32_T - b_index)) {
          b_index = MAX_int32_T;
        } else {
          b_index += qY;
        }
      }
    }
  }
  emxFree_real_T(&dataRead);
  /*  Close file */
  cfclose(fileid);
  i = y->size[0] * y->size[1];
  y->size[0] = 1;
  y->size[1] = b_index;
  emxEnsureCapacity_char_T(y, i);
  y_data = y->data;
  for (i = 0; i < b_index; i++) {
    y_data[i] = (signed char)buffer[i];
  }
}

/*
 * File trailer for readfile.c
 *
 * [EOF]
 */