arch/dos/comm/irqwrap.S

   1 /*
   2  * This file is part of DZComm.
   3  * Version : 0.6
   4  * Minor changes by Dim Zegebart (zager@post.comstar.ru) to run with Palantir
   5  */
   6
   7 /*         ______   ___    ___
   8  *        /\  _  \ /\_ \  /\_ \
   9  *        \ \ \L\ \\//\ \ \//\ \      __     __   _ __   ___
  10  *         \ \  __ \ \ \ \  \ \ \   /'__`\ /'_ `\/\`'__\/ __`\
  11  *          \ \ \/\ \ \_\ \_ \_\ \_/\  __//\ \L\ \ \ \//\ \L\ \
  12  *           \ \_\ \_\/\____\/\____\ \____\ \____ \ \_\\ \____/
  13  *            \/_/\/_/\/____/\/____/\/____/\/___L\ \/_/ \/___/
  14  *                                           /\____/
  15  *                                           \_/__/
  16  *      By Shawn Hargreaves,
  17  *      1 Salisbury Road,
  18  *      Market Drayton,
  19  *      Shropshire,
  20  *      England, TF9 1AJ.
  21  *
  22  *      The hardware interrupt wrappers used by the stuff in irq.c.
  23  *
  24  *      Thanks to Marcel de Kogel for identifying the problems Allegro was
  25  *      having with reentrant interrupts, and for suggesting this solution.
  26  *
  27  *      See readme.txt for copyright information.
  28  */
  29
  30
  31 #ifndef DJGPP
  32 #error This file should only be used by the djgpp version of Allegro
  33 #endif
  34
  35 #include "asmdefs.inc"
  36
  37 .text
  38
  39
  40
  41 #define WRAPPER(x)                                                         ; \
  42 .globl __irq_wrapper_##x                                                   ; \
  43    .align 4                                                                ; \
  44 __irq_wrapper_##x:                                                         ; \
  45    pushw %ds                              /* save registers */             ; \
  46    pushw %es                                                               ; \
  47    pushw %fs                                                               ; \
  48    pushw %gs                                                               ; \
  49    pushal                                                                  ; \
  50                                                                            ; \
  51    .byte 0x2e                             /* cs: override */               ; \
  52    movw ___djgpp_ds_alias, %ax                                             ; \
  53    movw %ax, %ds                          /* set up selectors */           ; \
  54    movw %ax, %es                                                           ; \
  55    movw %ax, %fs                                                           ; \
  56    movw %ax, %gs                                                           ; \
  57                                                                            ; \
  58    movl $IRQ_STACKS-1, %ecx               /* look for a free stack */      ; \
  59                                                                            ; \
  60 stack_search_loop_##x:                                                     ; \
  61    leal __irq_stack(, %ecx, 4), %ebx                                       ; \
  62    cmpl $0, (%ebx)                                                         ; \
  63    jnz found_stack_##x                    /* found one! */                 ; \
  64                                                                            ; \
  65    decl %ecx                                                               ; \
  66    jge stack_search_loop_##x                                               ; \
  67                                                                            ; \
  68    jmp get_out_##x                        /* oh shit.. */                  ; \
  69                                                                            ; \
  70 found_stack_##x:                                                           ; \
  71    movl %esp, %ecx                        /* old stack in ecx + dx */      ; \
  72    movw %ss, %dx                                                           ; \
  73                                                                            ; \
  74    movl (%ebx), %esp                      /* set up our stack */           ; \
  75    movw %ax, %ss                                                           ; \
  76                                                                            ; \
  77    movl $0, (%ebx)                        /* flag the stack is in use */   ; \
  78                                                                            ; \
  79    pushl %edx                             /* push old stack onto new */    ; \
  80    pushl %ecx                                                              ; \
  81    pushl %ebx                                                              ; \
  82                                                                            ; \
  83    cld                                    /* clear the direction flag */   ; \
  84                                                                            ; \
  85    movl __irq_handler + IRQ_HANDLER + IRQ_SIZE*x, %eax                     ; \
  86    call *%eax                             /* call the C handler */         ; \
  87                                                                            ; \
  88    popl %ebx                              /* restore the old stack */      ; \
  89    popl %ecx                                                               ; \
  90    popl %edx                                                               ; \
  91    movl %esp, (%ebx)                                                       ; \
  92    movw %dx, %ss                                                           ; \
  93    movl %ecx, %esp                                                         ; \
  94                                                                            ; \
  95    orl %eax, %eax                         /* check return value */         ; \
  96    jz get_out_##x                                                          ; \
  97                                                                            ; \
  98    popal                                  /* chain to old handler */       ; \
  99    popw %gs                                                                ; \
 100    popw %fs                                                                ; \
 101    popw %es                                                                ; \
 102    popw %ds                                                                ; \
 103    ljmp %cs:__irq_handler + IRQ_OLDVEC + IRQ_SIZE*x                        ; \
 104                                                                            ; \
 105 get_out_##x:                                                               ; \
 106    popal                                  /* iret */                       ; \
 107    popw %gs                                                                ; \
 108    popw %fs                                                                ; \
 109    popw %es                                                                ; \
 110    popw %ds                                                                ; \
 111    sti                                                                     ; \
 112    iret
 113
 114
 115
 116 WRAPPER(0);
 117 WRAPPER(1);
 118 WRAPPER(2);
 119 WRAPPER(3);
 120 WRAPPER(4);
 121 WRAPPER(5);
 122 WRAPPER(6);
 123 WRAPPER(7);
 124 WRAPPER(8);
 125 WRAPPER(9);
 126 WRAPPER(10);
 127 WRAPPER(11);
 128 WRAPPER(12);
 129 WRAPPER(13);
 130 WRAPPER(14);
 131 WRAPPER(15);
 132
 133
 134 .globl __irq_wrapper_0_end
 135    .align 4
 136 __irq_wrapper_0_end:
 137    ret
 138