Pros of Unicorn

• More comprehensive emulation capabilities, supporting multiple architectures
• Active development and larger community support
• Extensive API for fine-grained control over emulation

Cons of Unicorn

• Higher complexity and steeper learning curve
• Larger codebase and potentially higher resource usage
• May be overkill for simple disassembly tasks

Code Comparison

Udis86 (disassembly):

ud_t ud_obj;
ud_init(&ud_obj);
ud_set_input_buffer(&ud_obj, buffer, size);
ud_set_mode(&ud_obj, 32);
while (ud_disassemble(&ud_obj)) {
    printf("%s\n", ud_insn_asm(&ud_obj));
}

Unicorn (emulation):

from unicorn import *

mu = Uc(UC_ARCH_X86, UC_MODE_32)
mu.mem_map(0x1000, 0x1000)
mu.mem_write(0x1000, b"\x41\x4a")  # INC ecx; DEC edx
mu.emu_start(0x1000, 0x1002)
ecx = mu.reg_read(UC_X86_REG_ECX)

Summary

Udis86 is a lightweight disassembler focused on x86/x86-64, while Unicorn is a powerful multi-architecture CPU emulator. Udis86 is simpler and more suitable for basic disassembly tasks, whereas Unicorn offers comprehensive emulation capabilities but with increased complexity.

Pros of Capstone

• Multi-architecture support (x86, ARM, MIPS, PowerPC, etc.)
• More actively maintained with frequent updates
• Extensive documentation and community support

Cons of Capstone

• Larger codebase and memory footprint
• Steeper learning curve for beginners
• Potentially slower for simple disassembly tasks

Code Comparison

Udis86 example:

ud_t ud_obj;
ud_init(&ud_obj);
ud_set_input_buffer(&ud_obj, buffer, size);
ud_set_mode(&ud_obj, 32);
while (ud_disassemble(&ud_obj)) {
    printf("%s\n", ud_insn_asm(&ud_obj));
}

Capstone example:

csh handle;
cs_open(CS_ARCH_X86, CS_MODE_32, &handle);
cs_insn *insn;
size_t count = cs_disasm(handle, buffer, size, 0x1000, 0, &insn);
for (size_t j = 0; j < count; j++) {
    printf("%s\t%s\n", insn[j].mnemonic, insn[j].op_str);
}

Both libraries offer disassembly capabilities, but Capstone provides a more feature-rich and flexible solution at the cost of increased complexity. Udis86 is simpler and more lightweight, focusing specifically on x86/x86-64 architectures.

Pros of Zydis

• More actively maintained with frequent updates
• Supports a wider range of architectures (x86, x86-64, ARM, ARM64)
• Better performance and lower memory footprint

Cons of Zydis

• Steeper learning curve due to more complex API
• Larger codebase, which may increase compilation time

Code Comparison

Udis86 usage:

ud_t ud_obj;
ud_init(&ud_obj);
ud_set_input_buffer(&ud_obj, buffer, size);
ud_set_mode(&ud_obj, 64);
while (ud_disassemble(&ud_obj)) {
    printf("%s\n", ud_insn_asm(&ud_obj));
}

Zydis usage:

ZydisDecoder decoder;
ZydisDecoderInit(&decoder, ZYDIS_MACHINE_MODE_LONG_64, ZYDIS_ADDRESS_WIDTH_64);
ZydisDecodedInstruction instruction;
while (ZYAN_SUCCESS(ZydisDecoderDecodeBuffer(&decoder, buffer, size, &instruction))) {
    // Process instruction
}

Both libraries offer x86/x86-64 disassembly capabilities, but Zydis provides more features and better performance. Udis86 has a simpler API, making it easier to use for basic disassembly tasks. Zydis, while more complex, offers greater flexibility and support for additional architectures.

Pros of asmjit

• More comprehensive: Supports both x86 and ARM architectures
• Active development: Regular updates and contributions
• Versatile: Can be used for both assembly and disassembly

Cons of asmjit

• Steeper learning curve: More complex API due to its broader feature set
• Larger codebase: Potentially higher memory footprint

Code Comparison

asmjit example:

#include <asmjit/asmjit.h>

using namespace asmjit;

JitRuntime rt;
CodeHolder code;
code.init(rt.environment());

x86::Assembler a(&code);
a.mov(x86::eax, 42);
a.ret();

typedef int (*Func)(void);
Func fn;
Error err = rt.add(&fn, &code);

udis86 example:

#include <udis86.h>

ud_t ud_obj;
ud_init(&ud_obj);
ud_set_input_buffer(&ud_obj, buffer, size);
ud_set_mode(&ud_obj, 32);
ud_set_syntax(&ud_obj, UD_SYN_INTEL);

while (ud_disassemble(&ud_obj)) {
    printf("%s\n", ud_insn_asm(&ud_obj));
}

asmjit offers a more feature-rich environment for both assembly and disassembly, while udis86 focuses primarily on disassembly with a simpler API. asmjit's active development and broader architecture support make it more suitable for complex projects, whereas udis86 might be preferable for simpler disassembly tasks on x86 architectures.