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#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stdint.h>
#define ULONG uint32_t
#define USHORT uint16_t
#define UCHAR uint8_t
ULONG isdata[1000000]; /* each bit defines one byte as: code=0, data=1 */
extern void dis_asm(ULONG off, ULONG val, char *stg);
int static inline le2int(unsigned char* buf)
{
int32_t res = (buf[3] << 24) | (buf[2] << 16) | (buf[1] << 8) | buf[0];
return res;
}
int main(int argc, char **argv)
{
FILE *in, *out;
char *ptr, stg[256];
unsigned char buf[4];
ULONG pos, sz, val, loop;
int offset, offset1;
USHORT regid;
if(argc == 1 || strcmp(argv[1], "--help") == 0)
{ printf("Usage: arm_disass [input file]\n");
printf(" disassembles input file to 'disasm.txt'\n");
exit(-1);
}
in = fopen(argv[1], "rb");
if(in == NULL)
{ printf("Cannot open %s", argv[1]);
exit(-1);
}
out = fopen("disasm.txt", "w");
if(out == NULL) exit(-1);
fseek(in, 0, SEEK_END);
sz = ftell(in);
/* first loop only sets data/code tags */
for(loop=0; loop<2; loop++)
{
for(pos=0; pos<sz; pos+=4)
{
/* clear disassembler string start */
memset(stg, 0, 40);
/* read next code dword */
fseek(in, pos, SEEK_SET);
fread(buf, 1, 4, in);
val = le2int(buf);
/* check for data tag set: if 1 byte out of 4 is marked => assume data */
if((isdata[pos>>5] & (0xf << (pos & 31))) || (val & 0xffff0000) == 0)
{
sprintf(stg, "%6x: %08x", pos, val);
}
else
{
dis_asm(pos, val, stg);
/* check for instant mov operation */
if(memcmp(stg+17, "mov ", 4) == 0 && (ptr=strstr(stg, "0x")) != NULL)
{
regid = *(USHORT*)(stg+22);
sscanf(ptr+2, "%x", &offset);
if(ptr[-1] == '-')
offset = -offset;
}
else
/* check for add/sub operation */
if((ptr=strstr(stg, "0x")) != NULL
&& (memcmp(stg+17, "add ", 4) == 0 || memcmp(stg+17, "sub ", 4) == 0))
{
if(regid == *(USHORT*)(stg+22) && regid == *(USHORT*)(stg+26))
{
sscanf(ptr+2, "%x", &offset1);
if(ptr[-1] == '-')
offset1 = -offset1;
if(memcmp(stg+17, "add ", 4) == 0) offset += offset1;
else offset -= offset1;
/* add result to disassembler string */
sprintf(stg+strlen(stg), " <- 0x%x", offset);
}
else
regid = 0;
}
else
regid = 0;
/* check for const data */
if(memcmp(stg+26, "[pc, ", 5) == 0 && (ptr=strstr(stg, "0x")) != NULL)
{
sscanf(ptr+2, "%x", &offset);
if(ptr[-1] == '-')
offset = -offset;
/* add data tag */
isdata[(pos+offset+8)>>5] |= 1 << ((pos+offset+8) & 31);
/* add const data to disassembler string */
fseek(in, pos+offset+8, SEEK_SET);
fread(&buf, 1, 4, in);
offset = le2int(buf);
sprintf(stg+strlen(stg), " <- 0x%x", offset);
}
}
/* remove trailing spaces */
while(stg[strlen(stg)-1] == 32)
stg[strlen(stg)-1] = 0;
if(loop == 1)
fprintf(out, "%s\n", stg);
}
}
fclose(in);
return 0;
}
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