Place sd card sketch inside existing LED scoller sketch

Im a noob to Arduino programming, I would like to combine sd card sketch into an existing LED scroller sketch, below is my working LED scroller sketch without the sd card code.
On line 255 and 256 it gives " HELLO WORLD " " SAMPLE TEXT " being the wording that appears on the LED display, I want to relocate those words onto an sd card

#define PIXELS 60*1.6

#define PIXEL_PORT  PORTD  
#define PIXEL_DDR   DDRD  

static const uint8_t onBits=0b11111110;                                  

#define T1H  814    
#define T1L  438    

#define T0H  312    
#define T0L  936    



#define RES 500000  



#define NS_PER_SEC (1000000000L)          

#define CYCLES_PER_SEC (F_CPU)

#define NS_PER_CYCLE ( NS_PER_SEC / CYCLES_PER_SEC )

#define NS_TO_CYCLES(n) ( (n) / NS_PER_CYCLE )

static inline void sendBitx8(  const uint8_t row , const uint8_t colorbyte , const uint8_t onBits ) {  
              
    asm volatile (


      "L_%=: \n\r"  
      
      "out %[port], %[onBits] \n\t"                

      
      "mov r0, %[bitwalker] \n\t"                  
      "and r0, %[colorbyte] \n\t"                  
      "breq OFF_%= \n\t"                          

      
      "nop \n\t  "                                
      "out %[port], %[row]   \n\t"                  
                                                  
                                                    


      "nop \n\t nop \n\t "                          
      "nop \n\t nop \n\t "                          
      "nop \n\t nop \n\t "                          
      "nop \n\t "                                

      "out %[port], __zero_reg__ \n\t"              
                                                  
                                                    
                                                    
      "ror %[bitwalker] \n\t"                      
                  
      "brcs DONE_%= \n\t"                          
      "nop \n\t \n\t "                          
            
      "jmp L_%= \n\t"                            
                                                  
                                              
                                              
                                                  
                                                          
      "OFF_%=: \n\r"                            

      "out %[port], __zero_reg__ \n\t"              
                                                  
                                                    

      "ror %[bitwalker] \n\t"                      
                  
      "brcs DONE_%= \n\t"                          

      "nop \n\t nop \n\t "                          
      "nop \n\t nop \n\t "                          
      "nop \n\t nop \n\t "                                
      "nop \n\t nop \n\t "                                      
      "nop \n\t "                                              
            
      "jmp L_%= \n\t"                                
                                                      
                                                  
                                                  
      
            
      "DONE_%=: \n\t"

 
    
      ::
      [port]    "I" (_SFR_IO_ADDR(PIXEL_PORT)),
      [row]   "d" (row),
      [onBits]   "d" (onBits),
      [colorbyte]   "d" (colorbyte ),                    
      [bitwalker] "r" (0x80)                      

    );
                                  
    
    
}



void show() {
  delayMicroseconds( (RES / 1000UL) + 1);    
}



static inline void sendRowRGB( uint8_t row ,  uint8_t r,  uint8_t g,  uint8_t b ) {

  sendBitx8( row , g , onBits);    
  sendBitx8( row , r , onBits);
  sendBitx8( row , b , onBits);    
 
}

#define FONT_WIDTH 5      
#define INTERCHAR_SPACE 1
#define ASCII_OFFSET 0x20    

const uint8_t Font5x7[] PROGMEM = {
0x00,0x00,0x00,0x00,0x00,//  
0x00,0x00,0xfa,0x00,0x00,// !
0x00,0xe0,0x00,0xe0,0x00,// "
0x28,0xfe,0x28,0xfe,0x28,// #
//0x24,0x54,0xfe,0x54,0x48,// $ // default
0x12,0x7e,0x92,0x92,0x42,// $  //this is £
0xc4,0xc8,0x10,0x26,0x46,// %
0x6c,0x92,0xaa,0x44,0x0a,// &
0x00,0xa0,0xc0,0x00,0x00,// '
0x00,0x38,0x44,0x82,0x00,// (
0x00,0x82,0x44,0x38,0x00,// )
0x10,0x54,0x38,0x54,0x10,// *
0x10,0x10,0x7c,0x10,0x10,// +
0x00,0x0a,0x0c,0x00,0x00,// ,
0x10,0x10,0x10,0x10,0x10,// -
0x00,0x06,0x06,0x00,0x00,// .
0x04,0x08,0x10,0x20,0x40,// /
0x7c,0x8a,0x92,0xa2,0x7c,// 0
0x00,0x42,0xfe,0x02,0x00,// 1
0x42,0x86,0x8a,0x92,0x62,// 2
0x84,0x82,0xa2,0xd2,0x8c,// 3
0x18,0x28,0x48,0xfe,0x08,// 4
0xe4,0xa2,0xa2,0xa2,0x9c,// 5
0x3c,0x52,0x92,0x92,0x0c,// 6
0x80,0x8e,0x90,0xa0,0xc0,// 7
0x6c,0x92,0x92,0x92,0x6c,// 8
0x60,0x92,0x92,0x94,0x78,// 9
0x00,0x6c,0x6c,0x00,0x00,// :
0x00,0x6a,0x6c,0x00,0x00,// ;
0x00,0x10,0x28,0x44,0x82,// <
0x28,0x28,0x28,0x28,0x28,// =
0x82,0x44,0x28,0x10,0x00,// >
0x40,0x80,0x8a,0x90,0x60,// ?
0x4c,0x92,0x9e,0x82,0x7c,// @
0x7e,0x88,0x88,0x88,0x7e,// A
0xfe,0x92,0x92,0x92,0x6c,// B
0x7c,0x82,0x82,0x82,0x44,// C
0xfe,0x82,0x82,0x44,0x38,// D
0xfe,0x92,0x92,0x92,0x82,// E
0xfe,0x90,0x90,0x80,0x80,// F
0x7c,0x82,0x82,0x8a,0x4c,// G
0xfe,0x10,0x10,0x10,0xfe,// H
0x00,0x82,0xfe,0x82,0x00,// I
0x04,0x02,0x82,0xfc,0x80,// J
0xfe,0x10,0x28,0x44,0x82,// K
0xfe,0x02,0x02,0x02,0x02,// L
0xfe,0x40,0x20,0x40,0xfe,// M
0xfe,0x20,0x10,0x08,0xfe,// N
0x7c,0x82,0x82,0x82,0x7c,// O
0xfe,0x90,0x90,0x90,0x60,// P
0x7c,0x82,0x8a,0x84,0x7a,// Q
0xfe,0x90,0x98,0x94,0x62,// R
0x62,0x92,0x92,0x92,0x8c,// S
0x80,0x80,0xfe,0x80,0x80,// T
0xfc,0x02,0x02,0x02,0xfc,// U
0xf8,0x04,0x02,0x04,0xf8,// V
0xfe,0x04,0x18,0x04,0xfe,// W
0xc6,0x28,0x10,0x28,0xc6,// X
0xc0,0x20,0x1e,0x20,0xc0,// Y
0x86,0x8a,0x92,0xa2,0xc2,// Z
0x00,0x00,0xfe,0x82,0x82,// [
0x40,0x20,0x10,0x08,0x04,// (backslash)
0x82,0x82,0xfe,0x00,0x00,// ]
0x20,0x40,0x80,0x40,0x20,// ^
0x02,0x02,0x02,0x02,0x02,// _
0x00,0x80,0x40,0x20,0x00,// `
0x04,0x2a,0x2a,0x2a,0x1e,// a
0xfe,0x12,0x22,0x22,0x1c,// b

0x12,0x2a,0x2a,0x2a,0x04,// s

0x00,0x10,0x6c,0x82,0x00,// {
0x00,0x00,0xfe,0x00,0x00,// |
0x00,0x82,0x6c,0x10,0x00,// }
0x10,0x10,0x54,0x38,0x10,// ~
0x10,0x38,0x54,0x10,0x10,// 
};


static inline void sendChar( uint8_t c ,  uint8_t skip , uint8_t r,  uint8_t g,  uint8_t b ) {

  const uint8_t *charbase = Font5x7 + (( c -' ')* FONT_WIDTH ) ;

  uint8_t col=FONT_WIDTH;

  while (skip--) {
      charbase++;
      col--;    
  }
 
  while (col--) {
      sendRowRGB( pgm_read_byte_near( charbase++ ) , r , g , b );
  }    
 
  col=INTERCHAR_SPACE;
 
  while (col--) {

    sendRowRGB( 0 , r , g , b );    // Interchar space
    
  }
 
}


static inline void sendString( const char *s , uint8_t skip ,  const uint8_t r,  const uint8_t g,  const uint8_t b ) {

  unsigned int l=PIXELS/(FONT_WIDTH+INTERCHAR_SPACE);

  sendChar( *s , skip ,  r , g , b );   // First char is special case becuase it can be stepped for smooth scrolling
 
  while ( *(++s) && l--) {

    sendChar( *s , 0,  r , g , b );

  }

  show();
}

void setup() {
  PIXEL_DDR |= onBits;         // Set used pins to output mode
}

static char jabberText[] =
      
     " HELLO WORLD "
     " SAMPLE TEXT "
     ;

void loop() {
 
  const char *m = jabberText;
              
  while (*m) {      


      for( uint8_t step=0; step<FONT_WIDTH+INTERCHAR_SPACE  ; step++ ) {   // step though each column of the 1st char for smooth scrolling

         cli();
 
      
 
         sendString( m , step , 0x00, 0x00 , 0x40 );    // Nice and not-too-bright blue hue default//peaks at 3.27 amps over 1.6m
    
        
         sei();
        
      
         _delay_ms(25);   // this is best in vertical
    
 
      }

    m++;

  }


}

below is my basic sd card sketch which I have attempted to drop into the above sketch,

#include <SD.h>
#include <SPI.h>

int CS_PIN = 10;

File jabberText;

void setup()
{

  Serial.begin(9600);

  initializeSD();

  openFile("test.txt");
  Serial.println(readLine());

}

void loop() {
  
}

void initializeSD()
{
  //Serial.println("Initializing SD card...");
  pinMode(CS_PIN, OUTPUT);

  if (SD.begin())
  {
    return;
  }
}



int openFile(char filename[])
{
  jabberText = SD.open(filename);
  if (jabberText)
  {
    //Serial.println("File opened with success!");
    return 1;
  } else
  {
    Serial.println("Error opening file...");
    return 0;
  }
}

String readLine()
{
  String received = "";
  char ch;
  while (jabberText.available())
  {
    ch = jabberText.read();
    if (ch == '\n')
    {
      return String(received);
    }
    else
    {
      received += ch;
    }
  }
  return "";
}

Perhaps someone might give a a price to achieve this thanks Dave

To make your life simple, read a line from your file by using [url=https://www.arduino.cc/reference/en/language/functions/communication/stream/streamreadbytesuntil/]readBytesUntil()[/url] (waiting for an '\n') into a char buffer and then replace the '\n' by a '\0' to terminate a c-String then you can call the sendString() function

repeat to read next line until there is nothing left to read (the function returns 0)