I am getting some unexpected errors as shown in glcdfont.c , spi_module.c and ssd1306.c....someone pls assist me

[yashica]

*** Using Compiler 'V5.06 update 4 (build 422)', folder: 'C:\Keil_v5\ARM\ARMCC\Bin'
Rebuild target 'nrf51422_xxac'
compiling main.c...
compiling glcdfont.c...
..\..\..\glcdfont.c(13): warning:  #177-D: variable "font"  was declared but never referenced
  static const unsigned char font[] PROGMEM = {
..\..\..\glcdfont.c: 1 warning, 0 errors
compiling spi_module.c...
..\..\..\spi_module.c(41): error:  #20: identifier "nrf_drv_spi_event_t" is undefined
  static void spi_master_event_handler(nrf_drv_spi_event_t event)
..\..\..\spi_module.c: 0 warnings, 1 error
compiling ssd1306.c...
..\..\..\ssd1306.c(32): error:  #20: identifier "TWI1_IRQ" is undefined
      .irq         = TWI1_IRQ,
..\..\..\ssd1306.c(31): error:  #136: struct "<unnamed>"  has no field "p_reg"
      .p_reg       = NRF_TWI1,
..\..\..\ssd1306.c(61): error:  #20: identifier "TWI1_CONFIG_FREQUENCY" is undefined
          .frequency          = TWI1_CONFIG_FREQUENCY,
..\..\..\ssd1306.c(62): error:  #20: identifier "TWI1_CONFIG_IRQ_PRIORITY" is undefined
          .interrupt_priority = TWI1_CONFIG_IRQ_PRIORITY
..\..\..\ssd1306.c(577): warning:  #69-D: integer conversion resulted in truncation
          nrf_drv_twi_tx(&m_twi_master, _i2caddr, buffer, (
SD1306_LCDWIDTH * 
SD1306_LCDHEIGHT / 8), 
alse);
..\..\..\ssd1306.c: 1 warning, 4 errors

[YASH]

i wanted to interface an ssd1306 oled display 128x32 spi with nrf51422 on SDK 12.2.0...i have enabled TWI interface also...