VBE.h bunch of questions

Question

I have this project that I need to configure some stuff about the graphics card and it is given a vbe.h file that I have no idea how use it.

#ifndef __VBE_H
#define __VBE_H

#include <stdint.h>

/** @defgroup vbe vbe
 * @{
 *
 * Functions related to the VBE standard
 */

/** @name VBE Mode Info Block */
/**@{
 *
 * Packed VBE Mode Info Block 
 */ 

typedef struct {
  /*  Mandatory information for all VBE revisions */
  uint16_t ModeAttributes;  /**< @brief mode attributes */
  uint8_t WinAAttributes;       /**< @brief window A attributes */
  uint8_t WinBAttributes;       /**< @brief window B attributes */
  uint16_t WinGranularity;  /**< @brief window granularity */
  uint16_t WinSize;     /**< @brief window size */
  uint16_t WinASegment;     /**< @brief window A start segment */
  uint16_t WinBSegment;     /**< @brief window B start segment */
  phys_bytes WinFuncPtr;    /**< @brief real mode/far pointer to window function */
  uint16_t BytesPerScanLine;    /**< @brief bytes per scan line */

  /* Mandatory information for VBE 1.2 and above */

  uint16_t XResolution;         /**< @brief horizontal resolution in pixels/characters */
  uint16_t YResolution;         /**< @brief vertical resolution in pixels/characters */
  uint8_t XCharSize;        /**< @brief character cell width in pixels */
  uint8_t YCharSize;        /**< @brief character cell height in pixels */
  uint8_t NumberOfPlanes;       /**< @brief number of memory planes */
  uint8_t BitsPerPixel;         /**< @brief bits per pixel */
  uint8_t NumberOfBanks;        /**< @brief number of banks */
  uint8_t MemoryModel;      /**< @brief memory model type */
  uint8_t BankSize;     /**< @brief bank size in KB */
  uint8_t NumberOfImagePages;   /**< @brief number of images */
  uint8_t Reserved1;        /**< @brief reserved for page function */

  /* Direct Color fields (required for direct/6 and YUV/7 memory models) */

  uint8_t RedMaskSize;      /* size of direct color red mask in bits */
  uint8_t RedFieldPosition; /* bit position of lsb of red mask */
  uint8_t GreenMaskSize;        /* size of direct color green mask in bits */
  uint8_t GreenFieldPosition;   /* bit position of lsb of green mask */
  uint8_t BlueMaskSize;         /* size of direct color blue mask in bits */
  uint8_t BlueFieldPosition;    /* bit position of lsb of blue mask */
  uint8_t RsvdMaskSize;     /* size of direct color reserved mask in bits */
  uint8_t RsvdFieldPosition;    /* bit position of lsb of reserved mask */
  uint8_t DirectColorModeInfo;  /* direct color mode attributes */

  /* Mandatory information for VBE 2.0 and above */
  phys_bytes PhysBasePtr;       /**< @brief physical address for flat memory frame buffer */
  uint8_t Reserved2[4];         /**< @brief Reserved - always set to 0 */
  uint8_t Reserved3[2];         /**< @brief Reserved - always set to 0 */

  /* Mandatory information for VBE 3.0 and above */
  uint16_t LinBytesPerScanLine;    /* bytes per scan line for linear modes */
  uint8_t BnkNumberOfImagePages;    /* number of images for banked modes */
  uint8_t LinNumberOfImagePages;    /* number of images for linear modes */
  uint8_t LinRedMaskSize;           /* size of direct color red mask (linear modes) */
  uint8_t LinRedFieldPosition;  /* bit position of lsb of red mask (linear modes) */
  uint8_t LinGreenMaskSize;     /* size of direct color green mask (linear modes) */
  uint8_t LinGreenFieldPosition; /* bit position of lsb of green mask (linear  modes) */
  uint8_t LinBlueMaskSize;  /* size of direct color blue mask (linear modes) */
  uint8_t LinBlueFieldPosition;     /* bit position of lsb of blue mask (linear modes ) */
  uint8_t LinRsvdMaskSize;  /* size of direct color reserved mask (linear modes) */
  uint8_t LinRsvdFieldPosition;  /* bit position of lsb of reserved mask (linear modes) */
  uint32_t MaxPixelClock;            /* maximum pixel clock (in Hz) for graphics mode */
  uint8_t Reserved4[190];        /* remainder of ModeInfoBlock */
} __attribute__((packed)) vbe_mode_info_t;

/** @} end of vbe_mode_info_t*/

/**
 * @brief Returns information on the input VBE mode, including screen dimensions, color depth and VRAM physical address
 * 
 * Initializes unpacked vbe_mode__info_t structure passed as an address with
 *  the information of the input mode, by calling VBE function 0x01
 *  Return VBE Mode Information and unpacking the ModeInfoBlock struct
 *  returned by that function.
 * 
 * @param mode mode whose information should be returned
 * @param vmi_p address of vbe_mode_info_t structure to be initialized
 * @return 0 on success, non-zero otherwise
 */
int vbe_get_mode_info(unsigned short mode, vbe_mode_info_t *vmi_p);

 /** @} end of vbe */

#endif /* __VBE_H */

I would like to know how do I use some functions there like RedMaskSize, RedFieldPosition and so on. Any idea?

regards

Answer 1

There's only one function there, vbe_get_mode_info. You call it with a pointer to your structure, give it a mode, and it fills up the structure for you:

vbe_mode_info_t params;
vbe_get_mode_info(0 /* guess at a mode */, &params);

// now you can use params.RedMaskSize for example as you want

Make sure you link your library when compiling, the documentation for this thing is here: http://web.fe.up.pt/~pfs/aulas/lcom2011/labs/lab2/doc/group__vbe.html