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Implementing a new analysis plugin

After implementing disassembly plugin, you might have noticed that output is far from being good - no proper highlighting, no reference lines and so on. This is because radare2 requires every architecture plugin to provide also analysis information about every opcode. At the moment the implementation of disassembly and opcodes analysis is separated between two modules - RAsm and RAnal. Thus we need to write an analysis plugin too.

The principle is very similar - you just need to create a C file and corresponding Makefile.

They structure of RAnal plugin looks like

RAnalPlugin r_anal_plugin_v810 = {
	.name = "mycpu",
	.desc = "MYCPU code analysis plugin",
	.license = "LGPL3",
	.arch = "mycpu",
	.bits = 32,
	.op = mycpu_op,
	.esil = true,
	.set_reg_profile = set_reg_profile,
};

Like with disassembly plugin there is a key function - `mycpu_op` which scans the opcode and builds RAnalOp structure. On the other hand, in this example analysis plugins also performs uplifting to ESIL, which is enabled in `.esil = true` statement. Thus, `mycpu_op` obliged to fill the corresponding RAnalOp ESIL field for the opcodes. Second important thing for ESIL uplifting and emulation - register profile, like in debugger, which is set within `set_reg_profile` function.

NAME=anal_snes
R2_PLUGIN_PATH=$(shell r2 -H R2_USER_PLUGINS)
LIBEXT=$(shell r2 -H LIBEXT)
CFLAGS=-g -fPIC $(shell pkg-config --cflags r_anal)
LDFLAGS=-shared $(shell pkg-config --libs r_anal)
OBJS=$(NAME).o
LIB=$(NAME).$(LIBEXT)

all: $(LIB)

clean:
	rm -f $(LIB) $(OBJS)

$(LIB): $(OBJS)
	$(CC) $(CFLAGS) $(LDFLAGS) $(OBJS) -o $(LIB)

install:
	cp -f anal_snes.$(SO_EXT) $(R2_PLUGIN_PATH)

uninstall:
	rm -f $(R2_PLUGIN_PATH)/anal_snes.$(SO_EXT)

/* radare - LGPL - Copyright 2015 - condret */

#include <string.h>
#include <r_types.h>
#include <r_lib.h>
#include <r_asm.h>
#include <r_anal.h>
#include "snes_op_table.h"

static int snes_anop(RAnal *anal, RAnalOp *op, ut64 addr, const ut8 *data, int len) {
	memset (op, '\0', sizeof (RAnalOp));
	op->size = snes_op[data[0]].len;
	op->addr = addr;
	op->type = R_ANAL_OP_TYPE_UNK;
	switch (data[0]) {
		case 0xea:
			op->type = R_ANAL_OP_TYPE_NOP;
			break;
	}
	return op->size;
}

struct r_anal_plugin_t r_anal_plugin_snes = {
	.name = "snes",
	.desc = "SNES analysis plugin",
	.license = "LGPL3",
	.arch = R_SYS_ARCH_NONE,
	.bits = 16,
	.init = NULL,
	.fini = NULL,
	.op = &snes_anop,
	.set_reg_profile = NULL,
	.fingerprint_bb = NULL,
	.fingerprint_fcn = NULL,
	.diff_bb = NULL,
	.diff_fcn = NULL,
	.diff_eval = NULL
};

#ifndef R2_PLUGIN_INCORE
R_API RLibStruct radare_plugin = {
	.type = R_LIB_TYPE_ANAL,
	.data = &r_anal_plugin_snes,
	.version = R2_VERSION
};
#endif

After compiling radare2 will list this plugin in the output: ``` _dA_ _8_16 snes LGPL3 SuperNES CPU ```

Example: