diff options
Diffstat (limited to 'disassembler.c')
| -rw-r--r-- | disassembler.c | 174 |
1 files changed, 174 insertions, 0 deletions
diff --git a/disassembler.c b/disassembler.c new file mode 100644 index 0000000..24bbc50 --- /dev/null +++ b/disassembler.c @@ -0,0 +1,174 @@ +#include <stdio.h> +#include <stdlib.h> +#include <stdint.h> +#include <errno.h> + +#include "util.h" + +void print_help(const char *argv0) +{ + fprintf(stderr, "Syntax: %s <in.bin>\0 <out.asm>\n", argv0); +} + +int disasm_rtype(uint16_t i, uint16_t unused) +{ + const char *oper = get_asm_from_oper(GET_OPER(i)); + const char *dest = get_asm_from_reg(GET_REG_DEST(i)); + const char *left = get_asm_from_reg(GET_REG_LEFT(i)); + const char *right = get_asm_from_reg(GET_REG_RIGHT(i)); + + /* FIXME add special cases: + * - nop + * - neg + * - mv + */ + printf("%s %s, %s, %s\n", oper, dest, left, right); + + return 0; +} + +int disasm_nitype(uint16_t i, uint16_t unused) +{ + const char *oper = get_asm_from_oper(GET_OPER(i)); + const char *dest = get_asm_from_reg(GET_REG_DEST(i)); + const char *left = get_asm_from_reg(GET_REG_LEFT(i)); + uint16_t imm = GET_NI_IMM(i); + /** FIXME add special cases: + * - ldi + */ + /* FIXME review sign around immediate value */ + printf("%si %s, %s, 0x%x\n", oper, dest, left, imm); + return 0; +} + +int disasm_witype(uint16_t i, uint16_t unused) +{ + const char *oper = get_asm_from_oper(GET_OPER(i)); + const char *dest = get_asm_from_reg(GET_REG_DEST(i)); + const char *left = get_asm_from_reg(GET_REG_LEFT(i)); + uint16_t imm = GET_NI_IMM(i); + /* FIXME handle wide imm value */ + printf("%si, %s, %s, 0x%x\n", "oper", dest, left, "?"); + return 0; +} + +int disasm_jreg(uint16_t i, uint16_t unused) +{ + const char *inst = get_asm_from_j(GET_JB_COND(i)); + const char *reg = get_asm_from_reg(GET_JUMP_REG(i)); + printf("%s %s\n", inst, reg); + return 0; +} + +int disasm_bimm(uint16_t i, uint16_t unused) +{ + const char *inst = get_asm_from_b(GET_JB_COND(i)); + /* FIXME immediate value is meant to be signed */ + printf("%s 0x%x\n", inst, GET_B_OFFSET(i)); + return 0; +} + +int disasm_jimm(uint16_t i, uint16_t imm) +{ + const char *inst = get_asm_from_j(GET_JB_COND(i)); + printf("%s 0x%x\n", inst, imm); + return 0; +} + +int disasm(FILE *f) +{ + int ret = 0; + size_t offs = 0; + size_t extra_read = 0; + uint16_t inst = 0; + uint8_t c[2] = { 0 }; + int (*disasm_inst)(uint16_t, uint16_t); + + while (!feof(f) && fread(c, sizeof(c), 1, f) == 1) { + extra_read = 0; + inst = c[0] << 8 | c[1]; + switch (GET_INST_TYPE(inst)) { + case INST_TYPE_RTYPE: + disasm_inst = disasm_rtype; + break; + case INST_TYPE_NITYPE: + disasm_inst = disasm_nitype; + break; + case INST_TYPE_WITYPE: + if (fread(c, sizeof(c), 1, f) != 1) { + ret = -errno; + break; + } + extra_read = sizeof(c); + disasm_inst = disasm_witype; + break; + case INST_TYPE_JTYPE: + /* J Type can be split into three further subtypes: + * - branch (always immediate, 2 bytes) + * - jump reg (2 bytes) + * - jump immediate (4 bytes) + */ + if (inst & MASK_IS_BRANCH) { + disasm_inst = disasm_bimm; + } else { + if (inst & MASK_JR) { + disasm_inst = disasm_jreg; + } else { + if (fread(c, sizeof(c), 1, f) != 1) { + ret = -errno; + break; + } + extra_read = sizeof(c); + disasm_inst = disasm_jimm; + } + } + break; + default: + printf("Unhandled instruction at byte %zd\n", offs); + ret = -1; + break; + } + /* Fall out of loop if picking a handler errored */ + if (ret) { + break; + } + printf("%04x:\t", offs); + ret = disasm_inst(inst, c[0] << 8 | c[1]); + if (ret < 0) { + fprintf(stderr, "Error handling instruction at byte %zd\n", offs); + break; + } + offs += sizeof(c) + extra_read; + } + + if (!feof(f)) { + perror("fread"); + ret = errno; + } else { + /* print out final, empty label */ + printf("%04x:\n", offs); + } + + return ret; +} + +int main(int argc, char **argv) +{ + int ret = 0; + FILE *fin = NULL; + + if (argc < 2) { + print_help(argv[0]); + return 1; + } + + if (!(fin = fopen(argv[1], "rb"))) { + perror("fopen"); + return 1; + } + + ret = disasm(fin); + + fclose(fin); + return ret; +} |