install.c

软中断处理程序

/***************************/
/* File: install.c */
/* Author: Andy Beeson */
/* Date: 7th February 1994 */
/***************************/
#include <stdio.h>
#include <stdlib.h>
extern void SWIHandler (void);
extern void MakeChain (void);
unsigned *Dswivec =(unsigned *)0x20; /*ie place to store old one*/
struct four_results
{ unsigned a;
unsigned b;
unsigned c;
unsigned d;
};
__swi (256) void my_swi_256 (void);
__swi (257) void my_swi_257 (unsigned);
__swi (258) unsigned my_swi_258
(unsigned,unsigned,unsigned,unsigned);
__swi (259) __value_in_regs struct four_results
my_swi_259 (unsigned, unsigned, unsigned,unsigned);
unsigned Install_Handler (unsigned routine, unsigned *vector)
/* Updates contents of 'vector' to contain branch instruction */
/* to reach 'routine' from 'vector'. Function return value is */
/* original contents of 'vector'. */
/* NB: 'Routine' must be within range of 32Mbytes from 'vector'. */
{ unsigned vec, oldvec;
vec = ((routine - (unsigned)vector - 0x8)>>2);
if (vec & 0xff000000)
{ printf ("Installation of Handler failed");
exit (0);
}
vec = 0xea000000 | vec;
oldvec = *vector;
*vector = vec;
return (oldvec);
}
void Update_Demon_Vec (unsigned *original, unsigned *Dvec)
/* Returns updated instruction 'LDR pc, [pc,#offset]' when */
/* moved from 'original' to 'Dvec' (ie recalculates offset). */
/* Assumes 'Dvec' is higher in memory than 'original'. */
{
*Dvec = ((*Dvec &0xfff)
- ((unsigned) Dvec - (unsigned) original))
| (*Dvec & 0xfffff000);
}
unsigned C_SWI_Handler (unsigned number, unsigned *reg)
{ unsigned done = 1;
/* Set up parameter storage block pointers */
unsigned *called_256 = (unsigned *) 0x24;
unsigned *param_257 = (unsigned*) 0x28;
unsigned *param_258 = (unsigned*) 0x2c; /* + 0x30,0x34,0x38 */
unsigned *param_259 = (unsigned*) 0x3c; /* + 0x40,0x44,0x48 */
switch (number)
{ case 256:
*called_256 = 256; /* Store a value to show that */
break; /* SWI was handled correctly. */
case 257:
*param_257 = reg [0]; /* Store parameter */
break;
case 258:
*param_258++ = reg [0]; /* Store parameters */
*param_258++ = reg [1];
*param_258++ = reg [2];
*param_258 = reg [3];
/* Now calculate result */
reg [0] += reg [1] + reg [2] + reg [3];
break;
case 259:
*param_259++ = reg [0]; /* Store parameters */
*param_259++ = reg [1];
*param_259++ = reg [2];
*param_259 = reg [3];
reg [0] *= 2; /* Calculate results */
reg [1] *= 3;
reg [2] *= 4;
reg [3] *= 5;
break;
default: done = 0; /* SWI not handled */
}
return (done);
}
int main ()
{
struct four_results r_259; /* Results from SWI 259 */
unsigned *swivec = (unsigned *)0x8; /* Pointer to SWI vector */
*Dswivec = Install_Handler ((unsigned)SWIHandler, swivec);
Update_Demon_Vec (swivec, Dswivec);
MakeChain ();
printf("Hello 256\n");
my_swi_256 ();
printf("Hello 257\n");
my_swi_257 (257);
printf("Hello 258\n");
printf(" Result = %u\n",my_swi_258 (1,2,3,4));
printf ("Hello 259\n");
r_259 = my_swi_259 (10,20,30,40);
printf (" Results are: %u %u %u %u\n",
r_259.a,r_259.b,r_259.c,r_259.d);
printf("The end\n");
return (0);
}