prj/tech/libsrc/dev2d/bank.h

   1 /*
   2  * $Source: s:/prj/tech/libsrc/dev2d/RCS/bank.h $
   3  * $Revision: 1.1 $
   4  * $Author: KEVIN $
   5  * $Date: 1996/04/10 16:41:23 $
   6  *
   7  * Declarations for bank-switching.  Lots of gruesome stuff
   8  * to make things efficient, but still allow drawing in interrupt.
   9  *
  10  * This file is part of the dev2d library.
  11  *
  12  */
  13
  14 #ifndef __BANK_H
  15 #define __BANK_H
  16
  17 #include <grd.h>
  18 #include <idevice.h>
  19
  20 #ifdef __cplusplus
  21 extern "C" {
  22 #endif
  23
  24 extern volatile int gdd_bank;
  25 extern volatile int gdd_ignore_bank;
  26 extern volatile int gdd_save_bank;
  27
  28 // a pointer to the function that actually sets the bank
  29 #define gd_force_bank \
  30          ((void (*)(int bank))grd_device_table[GDC_SET_BANK])
  31
  32 // gd_inc_bank sets the semaphore to indicate gdd_bank is unreliable,
  33 // increments and sets the bank, and resets the unreliability semaphore.
  34 #define gd_inc_bank() \
  35    do {                          \
  36       gdd_ignore_bank++;         \
  37       gd_force_bank(++gdd_bank); \
  38       gdd_ignore_bank--;         \
  39    } while (0)
  40
  41 // gd_set_bank sets a semaphore to indicate that the bank must be
  42 // restored by any primitive subsequently called (in interrupt,
  43 // generally).
  44 // use exactly once per primitive.  always use gd_restore_bank
  45 // before exiting.
  46
  47 #define gd_set_bank(b) \
  48    do {                         \
  49       gdd_save_bank++;          \
  50       if (gdd_ignore_bank!=0) { \
  51          gdd_bank = b;          \
  52          gd_force_bank(b);      \
  53          break;                 \
  54       }                         \
  55       if (gdd_bank != b) {      \
  56          gdd_ignore_bank++;     \
  57          gdd_bank = b;          \
  58          gd_force_bank(b);      \
  59          gdd_ignore_bank--;     \
  60       }                         \
  61    } while (0)
  62
  63 // gd_restore_bank decrements the save semaphore and resets
  64 // the bank when necessary.
  65
  66 #define gd_restore_bank(sb) \
  67    do {                             \
  68       gdd_save_bank--;              \
  69       if ((gdd_save_bank!=0)&&      \
  70           (sb!=gdd_bank)) {         \
  71          gdd_bank = sb;             \
  72          gd_force_bank(gdd_bank);   \
  73       }                             \
  74    } while (0)
  75
  76 /* calculates a video memory pointer from offset p. */
  77 #define gd_bank_p(p) \
  78    ((uchar *) grd_cap->vbase+((p)&0xffff))
  79
  80 #ifdef __cplusplus
  81 };
  82 #endif
  83 #endif /* !__BANK_H */