usbh_hid_parser.c

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/* Includes ------------------------------------------------------------------*/
#include "usbh_hid_parser.h"


uint32_t HID_ReadItem(HID_Report_ItemTypedef *ri, uint8_t ndx)
{
  uint32_t val=0;
  uint32_t x=0;
  uint32_t bofs;
  uint8_t *data=ri->data;
  uint8_t shift=ri->shift;
  
  /* get the logical value of the item */
  
  /* if this is an array, wee may need to offset ri->data.*/
  if (ri->count > 0)
  { 
    /* If app tries to read outside of the array. */
    if (ri->count <= ndx)
    {
      return(0);
    }
    
    /* calculate bit offset */
    bofs = ndx*ri->size;
    bofs += shift;
    /* calculate byte offset + shift pair from bit offset. */    
    data+=bofs/8;
    shift=(uint8_t)(bofs%8);
  }
  /* read data bytes in little endian order */
  for(x=0; x < ((ri->size & 0x7) ? (ri->size/8)+1 : (ri->size/8)); x++)
  {
    val=(uint32_t)(*data << (x*8));
  }    
  val=(val >> shift) & ((1<<ri->size)-1);
  
  if (val < ri->logical_min || val > ri->logical_max)
  {
    return(0);
  }
  
  /* convert logical value to physical value */
  /* See if the number is negative or not. */
  if ((ri->sign) && (val & (1<<(ri->size-1))))
  {
    /* yes, so sign extend value to 32 bits. */
    int vs=(int)((-1 & ~((1<<(ri->size))-1)) | val);
    
    if(ri->resolution == 1)
    {
      return((uint32_t)vs);
    }
    return((uint32_t)(vs*ri->resolution));
  }
  else
  {
    if(ri->resolution == 1)
    {
      return(val);
    }
    return(val*ri->resolution);    
  }  
}

uint32_t HID_WriteItem(HID_Report_ItemTypedef *ri, uint32_t value, uint8_t ndx)
{
  uint32_t x;
  uint32_t mask;
  uint32_t bofs;
  uint8_t *data=ri->data;
  uint8_t shift=ri->shift;
  
  if (value < ri->physical_min || value > ri->physical_max)  
  {
    return(1);
  }
  
    /* if this is an array, wee may need to offset ri->data.*/
  if (ri->count > 0)
  { 
    /* If app tries to read outside of the array. */
    if (ri->count >= ndx)
    {
      return(0);
    }
    /* calculate bit offset */
    bofs = ndx*ri->size;
    bofs += shift;
    /* calculate byte offset + shift pair from bit offset. */    
    data+=bofs/8;
    shift=(uint8_t)(bofs%8);

  }

  /* Convert physical value to logical value. */  
  if (ri->resolution != 1)
  {
    value=value/ri->resolution;
  }

  /* Write logical value to report in little endian order. */
  mask=(uint32_t)((1<<ri->size)-1);
  value = (value & mask) << shift;
  
  for(x=0; x < ((ri->size & 0x7) ? (ri->size/8)+1 : (ri->size/8)); x++)
  {
    *(ri->data+x)=(uint8_t)((*(ri->data+x) & ~(mask>>(x*8))) | ((value>>(x*8)) & (mask>>(x*8))));
  }
  return(0);
}

/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/