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/* Capstone Disassembly Engine */
/* By Nguyen Anh Quynh <>, 2015-2019 */
// This sample code demonstrates the option CS_OPT_MNEMONIC
// to customize instruction mnemonic.
#include <stdio.h>
#include <stdlib.h>
#include <capstone/platform.h>
#include <capstone/capstone.h>
#define X86_CODE32 "\x75\x01"
// Print out the input code in hexadecimal format
static void print_string_hex(unsigned char *str, size_t len)
unsigned char *c;
for (c = str; c < str + len; c++) {
printf("%02x ", *c & 0xff);
// Print one instruction
static void print_insn(csh handle)
cs_insn *insn;
size_t count;
count = cs_disasm(handle, (const uint8_t *)X86_CODE32, sizeof(X86_CODE32) - 1, 0x1000, 1, &insn);
if (count) {
print_string_hex((unsigned char *)X86_CODE32, sizeof(X86_CODE32) - 1);
printf("\t%s\t%s\n", insn[0].mnemonic, insn[0].op_str);
// Free memory allocated by cs_disasm()
cs_free(insn, count);
} else {
printf("ERROR: Failed to disasm given code!\n");
static void test()
csh handle;
cs_err err;
// Customize mnemonic JNE to "jnz"
cs_opt_mnem my_mnem = { X86_INS_JNE, "jnz" };
// Set .mnemonic to NULL to reset to default mnemonic
cs_opt_mnem default_mnem = { X86_INS_JNE, NULL };
err = cs_open(CS_ARCH_X86, CS_MODE_32, &handle);
if (err) {
printf("Failed on cs_open() with error returned: %u\n", err);
// 1. Print out the instruction in default setup.
printf("Disassemble X86 code with default instruction mnemonic\n");
// Customized mnemonic JNE to JNZ using CS_OPT_MNEMONIC option
printf("\nNow customize engine to change mnemonic from 'JNE' to 'JNZ'\n");
cs_option(handle, CS_OPT_MNEMONIC, (size_t)&my_mnem);
// 2. Now print out the instruction in newly customized setup.
// Reset engine to use the default mnemonic of JNE
printf("\nReset engine to use the default mnemonic\n");
cs_option(handle, CS_OPT_MNEMONIC, (size_t)&default_mnem);
// 3. Now print out the instruction in default setup.
// Done
int main()
return 0;