/* disasm.c where all the _work_ gets done in the Netwide Disassembler * * The Netwide Assembler is copyright (C) 1996 Simon Tatham and * Julian Hall. All rights reserved. The software is * redistributable under the license given in the file "LICENSE" * distributed in the NASM archive. * * initial version 27/iii/95 by Simon Tatham */ #include "compiler.h" #include #include #include #include #include "nasm.h" #include "disasm.h" #include "sync.h" #include "insns.h" #include "tables.h" #include "regdis.h" /* * Flags that go into the `segment' field of `insn' structures * during disassembly. */ #define SEG_RELATIVE 1 #define SEG_32BIT 2 #define SEG_RMREG 4 #define SEG_DISP8 8 #define SEG_DISP16 16 #define SEG_DISP32 32 #define SEG_NODISP 64 #define SEG_SIGNED 128 #define SEG_64BIT 256 /* * Prefix information */ struct prefix_info { uint8_t osize; /* Operand size */ uint8_t asize; /* Address size */ uint8_t osp; /* Operand size prefix present */ uint8_t asp; /* Address size prefix present */ uint8_t rep; /* Rep prefix present */ uint8_t seg; /* Segment override prefix present */ uint8_t wait; /* WAIT "prefix" present */ uint8_t lock; /* Lock prefix present */ uint8_t vex[3]; /* VEX prefix present */ uint8_t vex_m; /* VEX.M field */ uint8_t vex_v; uint8_t vex_lp; /* VEX.LP fields */ uint32_t rex; /* REX prefix present */ }; #define getu8(x) (*(uint8_t *)(x)) #if X86_MEMORY /* Littleendian CPU which can handle unaligned references */ #define getu16(x) (*(uint16_t *)(x)) #define getu32(x) (*(uint32_t *)(x)) #define getu64(x) (*(uint64_t *)(x)) #else static uint16_t getu16(uint8_t *data) { return (uint16_t)data[0] + ((uint16_t)data[1] << 8); } static uint32_t getu32(uint8_t *data) { return (uint32_t)getu16(data) + ((uint32_t)getu16(data+2) << 16); } static uint64_t getu64(uint8_t *data) { return (uint64_t)getu32(data) + ((uint64_t)getu32(data+4) << 32); } #endif #define gets8(x) ((int8_t)getu8(x)) #define gets16(x) ((int16_t)getu16(x)) #define gets32(x) ((int32_t)getu32(x)) #define gets64(x) ((int64_t)getu64(x)) /* Important: regval must already have been adjusted for rex extensions */ static enum reg_enum whichreg(int32_t regflags, int regval, int rex) { if (!(regflags & (REGISTER|REGMEM))) return 0; /* Registers not permissible?! */ regflags |= REGISTER; if (!(REG_AL & ~regflags)) return R_AL; if (!(REG_AX & ~regflags)) return R_AX; if (!(REG_EAX & ~regflags)) return R_EAX; if (!(REG_RAX & ~regflags)) return R_RAX; if (!(REG_DL & ~regflags)) return R_DL; if (!(REG_DX & ~regflags)) return R_DX; if (!(REG_EDX & ~regflags)) return R_EDX; if (!(REG_RDX & ~regflags)) return R_RDX; if (!(REG_CL & ~regflags)) return R_CL; if (!(REG_CX & ~regflags)) return R_CX; if (!(REG_ECX & ~regflags)) return R_ECX; if (!(REG_RCX & ~regflags)) return R_RCX; if (!(FPU0 & ~regflags)) return R_ST0; if (!(XMM0 & ~regflags)) return R_XMM0; if (!(YMM0 & ~regflags)) return R_YMM0; if (!(REG_CS & ~regflags)) return (regval == 1) ? R_CS : 0; if (!(REG_DESS & ~regflags)) return (regval == 0 || regval == 2 || regval == 3 ? nasm_rd_sreg[regval] : 0); if (!(REG_FSGS & ~regflags)) return (regval == 4 || regval == 5 ? nasm_rd_sreg[regval] : 0); if (!(REG_SEG67 & ~regflags)) return (regval == 6 || regval == 7 ? nasm_rd_sreg[regval] : 0); /* All the entries below look up regval in an 16-entry array */ if (regval < 0 || regval > 15) return 0; if (!(REG8 & ~regflags)) { if (rex & REX_P) return nasm_rd_reg8_rex[regval]; else return nasm_rd_reg8[regval]; } if (!(REG16 & ~regflags)) return nasm_rd_reg16[regval]; if (!(REG32 & ~regflags)) return nasm_rd_reg32[regval]; if (!(REG64 & ~regflags)) return nasm_rd_reg64[regval]; if (!(REG_SREG & ~regflags)) return nasm_rd_sreg[regval & 7]; /* Ignore REX */ if (!(REG_CREG & ~regflags)) return nasm_rd_creg[regval]; if (!(REG_DREG & ~regflags)) return nasm_rd_dreg[regval]; if (!(REG_TREG & ~regflags)) { if (rex & REX_P) return 0; /* TR registers are ill-defined with rex */ return nasm_rd_treg[regval]; } if (!(FPUREG & ~regflags)) return nasm_rd_fpureg[regval & 7]; /* Ignore REX */ if (!(MMXREG & ~regflags)) return nasm_rd_mmxreg[regval & 7]; /* Ignore REX */ if (!(XMMREG & ~regflags)) return nasm_rd_xmmreg[regval]; if (!(YMMREG & ~regflags)) return nasm_rd_ymmreg[regval]; return 0; } /* * Process a DREX suffix */ static uint8_t *do_drex(uint8_t *data, insn *ins) { uint8_t drex = *data++; operand *dst = &ins->oprs[ins->drexdst]; if ((drex & 8) != ((ins->rex & REX_OC) ? 8 : 0)) return NULL; /* OC0 mismatch */ ins->rex = (ins->rex & ~7) | (drex & 7); dst->segment = SEG_RMREG; dst->basereg = drex >> 4; return data; } /* * Process an effective address (ModRM) specification. */ static uint8_t *do_ea(uint8_t *data, int modrm, int asize, int segsize, operand * op, insn *ins) { int mod, rm, scale, index, base; int rex; uint8_t sib = 0; mod = (modrm >> 6) & 03; rm = modrm & 07; if (mod != 3 && rm == 4 && asize != 16) sib = *data++; if (ins->rex & REX_D) { data = do_drex(data, ins); if (!data) return NULL; } rex = ins->rex; if (mod == 3) { /* pure register version */ op->basereg = rm+(rex & REX_B ? 8 : 0); op->segment |= SEG_RMREG; return data; } op->disp_size = 0; op->eaflags = 0; if (asize == 16) { /* * specifies the displacement size (none, byte or * word), and specifies the register combination. * Exception: mod=0,rm=6 does not specify [BP] as one might * expect, but instead specifies [disp16]. */ op->indexreg = op->basereg = -1; op->scale = 1; /* always, in 16 bits */ switch (rm) { case 0: op->basereg = R_BX; op->indexreg = R_SI; break; case 1: op->basereg = R_BX; op->indexreg = R_DI; break; case 2: op->basereg = R_BP; op->indexreg = R_SI; break; case 3: op->basereg = R_BP; op->indexreg = R_DI; break; case 4: op->basereg = R_SI; break; case 5: op->basereg = R_DI; break; case 6: op->basereg = R_BP; break; case 7: op->basereg = R_BX; break; } if (rm == 6 && mod == 0) { /* special case */ op->basereg = -1; if (segsize != 16) op->disp_size = 16; mod = 2; /* fake disp16 */ } switch (mod) { case 0: op->segment |= SEG_NODISP; break; case 1: op->segment |= SEG_DISP8; op->offset = (int8_t)*data++; break; case 2: op->segment |= SEG_DISP16; op->offset = *data++; op->offset |= ((unsigned)*data++) << 8; break; } return data; } else { /* * Once again, specifies displacement size (this time * none, byte or *dword*), while specifies the base * register. Again, [EBP] is missing, replaced by a pure * disp32 (this time that's mod=0,rm=*5*) in 32-bit mode, * and RIP-relative addressing in 64-bit mode. * * However, rm=4 * indicates not a single base register, but instead the * presence of a SIB byte... */ int a64 = asize == 64; op->indexreg = -1; if (a64) op->basereg = nasm_rd_reg64[rm | ((rex & REX_B) ? 8 : 0)]; else op->basereg = nasm_rd_reg32[rm | ((rex & REX_B) ? 8 : 0)]; if (rm == 5 && mod == 0) { if (segsize == 64) { op->eaflags |= EAF_REL; op->segment |= SEG_RELATIVE; mod = 2; /* fake disp32 */ } if (asize != 64) op->disp_size = asize; op->basereg = -1; mod = 2; /* fake disp32 */ } if (rm == 4) { /* process SIB */ scale = (sib >> 6) & 03; index = (sib >> 3) & 07; base = sib & 07; op->scale = 1 << scale; if (index == 4 && !(rex & REX_X)) op->indexreg = -1; /* ESP/RSP cannot be an index */ else if (a64) op->indexreg = nasm_rd_reg64[index | ((rex & REX_X) ? 8 : 0)]; else op->indexreg = nasm_rd_reg32[index | ((rex & REX_X) ? 8 : 0)]; if (base == 5 && mod == 0) { op->basereg = -1; mod = 2; /* Fake disp32 */ } else if (a64) op->basereg = nasm_rd_reg64[base | ((rex & REX_B) ? 8 : 0)]; else op->basereg = nasm_rd_reg32[base | ((rex & REX_B) ? 8 : 0)]; if (segsize == 16) op->disp_size = 32; } switch (mod) { case 0: op->segment |= SEG_NODISP; break; case 1: op->segment |= SEG_DISP8; op->offset = gets8(data); data++; break; case 2: op->segment |= SEG_DISP32; op->offset = gets32(data); data += 4; break; } return data; } } /* * Determine whether the instruction template in t corresponds to the data * stream in data. Return the number of bytes matched if so. */ #define case4(x) case (x): case (x)+1: case (x)+2: case (x)+3 static int matches(const struct itemplate *t, uint8_t *data, const struct prefix_info *prefix, int segsize, insn *ins) { uint8_t *r = (uint8_t *)(t->code); uint8_t *origdata = data; bool a_used = false, o_used = false; enum prefixes drep = 0; enum prefixes dwait = 0; uint8_t lock = prefix->lock; int osize = prefix->osize; int asize = prefix->asize; int i, c; int op1, op2; struct operand *opx, *opy; uint8_t opex = 0; int s_field_for = -1; /* No 144/154 series code encountered */ bool vex_ok = false; int regmask = (segsize == 64) ? 15 : 7; for (i = 0; i < MAX_OPERANDS; i++) { ins->oprs[i].segment = ins->oprs[i].disp_size = (segsize == 64 ? SEG_64BIT : segsize == 32 ? SEG_32BIT : 0); } ins->condition = -1; ins->rex = prefix->rex; memset(ins->prefixes, 0, sizeof ins->prefixes); if (t->flags & (segsize == 64 ? IF_NOLONG : IF_LONG)) return false; if (prefix->rep == 0xF2) drep = P_REPNE; else if (prefix->rep == 0xF3) drep = P_REP; dwait = prefix->wait ? P_WAIT : 0; while ((c = *r++) != 0) { op1 = (c & 3) + ((opex & 1) << 2); op2 = ((c >> 3) & 3) + ((opex & 2) << 1); opx = &ins->oprs[op1]; opy = &ins->oprs[op2]; opex = 0; switch (c) { case 01: case 02: case 03: case 04: while (c--) if (*r++ != *data++) return false; break; case 05: case 06: case 07: opex = c; break; case4(010): { int t = *r++, d = *data++; if (d < t || d > t + 7) return false; else { opx->basereg = (d-t)+ (ins->rex & REX_B ? 8 : 0); opx->segment |= SEG_RMREG; } break; } case4(014): case4(0274): opx->offset = (int8_t)*data++; opx->segment |= SEG_SIGNED; break; case4(020): opx->offset = *data++; break; case4(024): opx->offset = *data++; break; case4(030): opx->offset = getu16(data); data += 2; break; case4(034): if (osize == 32) { opx->offset = getu32(data); data += 4; } else { opx->offset = getu16(data); data += 2; } if (segsize != asize) opx->disp_size = asize; break; case4(040): case4(0254): opx->offset = getu32(data); data += 4; break; case4(044): switch (asize) { case 16: opx->offset = getu16(data); data += 2; if (segsize != 16) opx->disp_size = 16; break; case 32: opx->offset = getu32(data); data += 4; if (segsize == 16) opx->disp_size = 32; break; case 64: opx->offset = getu64(data); opx->disp_size = 64; data += 8; break; } break; case4(050): opx->offset = gets8(data++); opx->segment |= SEG_RELATIVE; break; case4(054): opx->offset = getu64(data); data += 8; break; case4(060): opx->offset = gets16(data); data += 2; opx->segment |= SEG_RELATIVE; opx->segment &= ~SEG_32BIT; break; case4(064): opx->segment |= SEG_RELATIVE; if (osize == 16) { opx->offset = gets16(data); data += 2; opx->segment &= ~(SEG_32BIT|SEG_64BIT); } else if (osize == 32) { opx->offset = gets32(data); data += 4; opx->segment &= ~SEG_64BIT; opx->segment |= SEG_32BIT; } if (segsize != osize) { opx->type = (opx->type & ~SIZE_MASK) | ((osize == 16) ? BITS16 : BITS32); } break; case4(070): opx->offset = gets32(data); data += 4; opx->segment |= SEG_32BIT | SEG_RELATIVE; break; case4(0100): case4(0110): case4(0120): case4(0130): { int modrm = *data++; opx->segment |= SEG_RMREG; data = do_ea(data, modrm, asize, segsize, opy, ins); if (!data) return false; opx->basereg = ((modrm >> 3) & 7) + (ins->rex & REX_R ? 8 : 0); break; } case4(0140): if (s_field_for == op1) { opx->offset = gets8(data); data++; } else { opx->offset = getu16(data); data += 2; } break; case4(0144): case4(0154): s_field_for = (*data & 0x02) ? op1 : -1; if ((*data++ & ~0x02) != *r++) return false; break; case4(0150): if (s_field_for == op1) { opx->offset = gets8(data); data++; } else { opx->offset = getu32(data); data += 4; } break; case4(0160): ins->rex |= REX_D; ins->drexdst = op1; break; case4(0164): ins->rex |= REX_D|REX_OC; ins->drexdst = op1; break; case 0171: data = do_drex(data, ins); if (!data) return false; break; case 0172: { uint8_t ximm = *data++; c = *r++; ins->oprs[c >> 3].basereg = (ximm >> 4) & regmask; ins->oprs[c >> 3].segment |= SEG_RMREG; ins->oprs[c & 7].offset = ximm & 15; } break; case 0173: { uint8_t ximm = *data++; c = *r++; if ((c ^ ximm) & 15) return false; ins->oprs[c >> 4].basereg = (ximm >> 4) & regmask; ins->oprs[c >> 4].segment |= SEG_RMREG; } break; case 0174: { uint8_t ximm = *data++; c = *r++; ins->oprs[c].basereg = (ximm >> 4) & regmask; ins->oprs[c].segment |= SEG_RMREG; } break; case4(0200): case4(0204): case4(0210): case4(0214): case4(0220): case4(0224): case4(0230): case4(0234): { int modrm = *data++; if (((modrm >> 3) & 07) != (c & 07)) return false; /* spare field doesn't match up */ data = do_ea(data, modrm, asize, segsize, opy, ins); if (!data) return false; break; } case4(0260): { int vexm = *r++; int vexwlp = *r++; ins->rex |= REX_V; if ((prefix->rex & (REX_V|REX_D|REX_P)) != REX_V) return false; if ((vexm & 0x1f) != prefix->vex_m) return false; switch (vexwlp & 030) { case 000: if (prefix->rex & REX_W) return false; break; case 010: if (!(prefix->rex & REX_W)) return false; ins->rex &= ~REX_W; break; case 020: /* VEX.W is a don't care */ ins->rex &= ~REX_W; break; case 030: break; } if ((vexwlp & 007) != prefix->vex_lp) return false; opx->segment |= SEG_RMREG; opx->basereg = prefix->vex_v; vex_ok = true; break; } case 0270: { int vexm = *r++; int vexwlp = *r++; ins->rex |= REX_V; if ((prefix->rex & (REX_V|REX_D|REX_P)) != REX_V) return false; if ((vexm & 0x1f) != prefix->vex_m) return false; switch (vexwlp & 030) { case 000: if (ins->rex & REX_W) return false; break; case 010: if (!(ins->rex & REX_W)) return false; break; default: break; /* Need to do anything special here? */ } if ((vexwlp & 007) != prefix->vex_lp) return false; if (prefix->vex_v != 0) return false; vex_ok = true; break; } case 0310: if (asize != 16) return false; else a_used = true; break; case 0311: if (asize == 16) return false; else a_used = true; break; case 0312: if (asize != segsize) return false; else a_used = true; break; case 0313: if (asize != 64) return false; else a_used = true; break; case 0314: if (prefix->rex & REX_B) return false; break; case 0315: if (prefix->rex & REX_X) return false; break; case 0316: if (prefix->rex & REX_R) return false; break; case 0317: if (prefix->rex & REX_W) return false; break; case 0320: if (osize != 16) return false; else o_used = true; break; case 0321: if (osize != 32) return false; else o_used = true; break; case 0322: if (osize != (segsize == 16) ? 16 : 32) return false; else o_used = true; break; case 0323: ins->rex |= REX_W; /* 64-bit only instruction */ osize = 64; o_used = true; break; case 0324: if (!(ins->rex & (REX_P|REX_W)) || osize != 64) return false; o_used = true; break; case 0330: { int t = *r++, d = *data++; if (d < t || d > t + 15) return false; else ins->condition = d - t; break; } case 0331: if (prefix->rep) return false; break; case 0332: if (prefix->rep != 0xF2) return false; drep = 0; break; case 0333: if (prefix->rep != 0xF3) return false; drep = 0; break; case 0334: if (lock) { ins->rex |= REX_R; lock = 0; } break; case 0335: if (drep == P_REP) drep = P_REPE; break; case 0336: case 0337: break; case 0340: return false; case 0341: if (prefix->wait != 0x9B) return false; dwait = 0; break; case4(0344): ins->oprs[0].basereg = (*data++ >> 3) & 7; break; case 0360: if (prefix->osp || prefix->rep) return false; break; case 0361: if (!prefix->osp || prefix->rep) return false; o_used = true; break; case 0362: if (prefix->osp || prefix->rep != 0xf2) return false; drep = 0; break; case 0363: if (prefix->osp || prefix->rep != 0xf3) return false; drep = 0; break; case 0364: if (prefix->osp) return false; break; case 0365: if (prefix->asp) return false; break; case 0366: if (!prefix->osp) return false; o_used = true; break; case 0367: if (!prefix->asp) return false; a_used = true; break; default: return false; /* Unknown code */ } } if (!vex_ok && (ins->rex & REX_V)) return false; /* REX cannot be combined with DREX or VEX */ if ((ins->rex & (REX_D|REX_V)) && (prefix->rex & REX_P)) return false; /* * Check for unused rep or a/o prefixes. */ for (i = 0; i < t->operands; i++) { if (ins->oprs[i].segment != SEG_RMREG) a_used = true; } if (lock) { if (ins->prefixes[PPS_LREP]) return false; ins->prefixes[PPS_LREP] = P_LOCK; } if (drep) { if (ins->prefixes[PPS_LREP]) return false; ins->prefixes[PPS_LREP] = drep; } ins->prefixes[PPS_WAIT] = dwait; if (!o_used) { if (osize != ((segsize == 16) ? 16 : 32)) { enum prefixes pfx = 0; switch (osize) { case 16: pfx = P_O16; break; case 32: pfx = P_O32; break; case 64: pfx = P_O64; break; } if (ins->prefixes[PPS_OSIZE]) return false; ins->prefixes[PPS_OSIZE] = pfx; } } if (!a_used && asize != segsize) { if (ins->prefixes[PPS_ASIZE]) return false; ins->prefixes[PPS_ASIZE] = asize == 16 ? P_A16 : P_A32; } /* Fix: check for redundant REX prefixes */ return data - origdata; } /* Condition names for disassembly, sorted by x86 code */ static const char * const condition_name[16] = { "o", "no", "c", "nc", "z", "nz", "na", "a", "s", "ns", "pe", "po", "l", "nl", "ng", "g" }; int32_t disasm(uint8_t *data, char *output, int outbufsize, int segsize, int32_t offset, int autosync, uint32_t prefer) { const struct itemplate * const *p, * const *best_p; const struct disasm_index *ix; uint8_t *dp; int length, best_length = 0; char *segover; int i, slen, colon, n; uint8_t *origdata; int works; insn tmp_ins, ins; uint32_t goodness, best; int best_pref; struct prefix_info prefix; bool end_prefix; memset(&ins, 0, sizeof ins); /* * Scan for prefixes. */ memset(&prefix, 0, sizeof prefix); prefix.asize = segsize; prefix.osize = (segsize == 64) ? 32 : segsize; segover = NULL; origdata = data; ix = itable; end_prefix = false; while (!end_prefix) { switch (*data) { case 0xF2: case 0xF3: prefix.rep = *data++; break; case 0x9B: prefix.wait = *data++; break; case 0xF0: prefix.lock = *data++; break; case 0x2E: segover = "cs", prefix.seg = *data++; break; case 0x36: segover = "ss", prefix.seg = *data++; break; case 0x3E: segover = "ds", prefix.seg = *data++; break; case 0x26: segover = "es", prefix.seg = *data++; break; case 0x64: segover = "fs", prefix.seg = *data++; break; case 0x65: segover = "gs", prefix.seg = *data++; break; case 0x66: prefix.osize = (segsize == 16) ? 32 : 16; prefix.osp = *data++; break; case 0x67: prefix.asize = (segsize == 32) ? 16 : 32; prefix.asp = *data++; break; case 0xC4: case 0xC5: if (segsize == 64 || (data[1] & 0xc0) == 0xc0) { prefix.vex[0] = *data++; prefix.vex[1] = *data++; prefix.rex = REX_V; if (prefix.vex[0] == 0xc4) { prefix.vex[2] = *data++; prefix.rex |= (~prefix.vex[1] >> 5) & 7; /* REX_RXB */ prefix.rex |= (prefix.vex[2] >> (7-3)) & REX_W; prefix.vex_m = prefix.vex[1] & 0x1f; prefix.vex_v = (~prefix.vex[2] >> 3) & 15; prefix.vex_lp = prefix.vex[2] & 7; } else { prefix.rex |= (~prefix.vex[1] >> (7-2)) & REX_R; prefix.vex_m = 1; prefix.vex_v = (~prefix.vex[1] >> 3) & 15; prefix.vex_lp = prefix.vex[1] & 7; } ix = itable_VEX[prefix.vex_m][prefix.vex_lp]; } end_prefix = true; break; case REX_P + 0x0: case REX_P + 0x1: case REX_P + 0x2: case REX_P + 0x3: case REX_P + 0x4: case REX_P + 0x5: case REX_P + 0x6: case REX_P + 0x7: case REX_P + 0x8: case REX_P + 0x9: case REX_P + 0xA: case REX_P + 0xB: case REX_P + 0xC: case REX_P + 0xD: case REX_P + 0xE: case REX_P + 0xF: if (segsize == 64) { prefix.rex = *data++; if (prefix.rex & REX_W) prefix.osize = 64; } end_prefix = true; break; default: end_prefix = true; break; } } best = -1; /* Worst possible */ best_p = NULL; best_pref = INT_MAX; if (!ix) return 0; /* No instruction table at all... */ dp = data; ix += *dp++; while (ix->n == -1) { ix = (const struct disasm_index *)ix->p + *dp++; } p = (const struct itemplate * const *)ix->p; for (n = ix->n; n; n--, p++) { if ((length = matches(*p, data, &prefix, segsize, &tmp_ins))) { works = true; /* * Final check to make sure the types of r/m match up. * XXX: Need to make sure this is actually correct. */ for (i = 0; i < (*p)->operands; i++) { if (!((*p)->opd[i] & SAME_AS) && ( /* If it's a mem-only EA but we have a register, die. */ ((tmp_ins.oprs[i].segment & SEG_RMREG) && !(MEMORY & ~(*p)->opd[i])) || /* If it's a reg-only EA but we have a memory ref, die. */ (!(tmp_ins.oprs[i].segment & SEG_RMREG) && !(REG_EA & ~(*p)->opd[i]) && !((*p)->opd[i] & REG_SMASK)) || /* Register type mismatch (eg FS vs REG_DESS): die. */ ((((*p)->opd[i] & (REGISTER | FPUREG)) || (tmp_ins.oprs[i].segment & SEG_RMREG)) && !whichreg((*p)->opd[i], tmp_ins.oprs[i].basereg, tmp_ins.rex)) )) { works = false; break; } } /* * Note: we always prefer instructions which incorporate * prefixes in the instructions themselves. This is to allow * e.g. PAUSE to be preferred to REP NOP, and deal with * MMX/SSE instructions where prefixes are used to select * between MMX and SSE register sets or outright opcode * selection. */ if (works) { int i, nprefix; goodness = ((*p)->flags & IF_PFMASK) ^ prefer; nprefix = 0; for (i = 0; i < MAXPREFIX; i++) if (tmp_ins.prefixes[i]) nprefix++; if (nprefix < best_pref || (nprefix == best_pref && goodness < best)) { /* This is the best one found so far */ best = goodness; best_p = p; best_pref = nprefix; best_length = length; ins = tmp_ins; } } } } if (!best_p) return 0; /* no instruction was matched */ /* Pick the best match */ p = best_p; length = best_length; slen = 0; /* TODO: snprintf returns the value that the string would have if * the buffer were long enough, and not the actual length of * the returned string, so each instance of using the return * value of snprintf should actually be checked to assure that * the return value is "sane." Maybe a macro wrapper could * be used for that purpose. */ for (i = 0; i < MAXPREFIX; i++) { const char *prefix = prefix_name(ins.prefixes[i]); if (prefix) slen += snprintf(output+slen, outbufsize-slen, "%s ", prefix); } i = (*p)->opcode; if (i >= FIRST_COND_OPCODE) slen += snprintf(output + slen, outbufsize - slen, "%s%s", nasm_insn_names[i], condition_name[ins.condition]); else slen += snprintf(output + slen, outbufsize - slen, "%s", nasm_insn_names[i]); colon = false; length += data - origdata; /* fix up for prefixes */ for (i = 0; i < (*p)->operands; i++) { opflags_t t = (*p)->opd[i]; const operand *o = &ins.oprs[i]; int64_t offs; if (t & SAME_AS) { o = &ins.oprs[t & ~SAME_AS]; t = (*p)->opd[t & ~SAME_AS]; } output[slen++] = (colon ? ':' : i == 0 ? ' ' : ','); offs = o->offset; if (o->segment & SEG_RELATIVE) { offs += offset + length; /* * sort out wraparound */ if (!(o->segment & (SEG_32BIT|SEG_64BIT))) offs &= 0xffff; else if (segsize != 64) offs &= 0xffffffff; /* * add sync marker, if autosync is on */ if (autosync) add_sync(offs, 0L); } if (t & COLON) colon = true; else colon = false; if ((t & (REGISTER | FPUREG)) || (o->segment & SEG_RMREG)) { enum reg_enum reg; reg = whichreg(t, o->basereg, ins.rex); if (t & TO) slen += snprintf(output + slen, outbufsize - slen, "to "); slen += snprintf(output + slen, outbufsize - slen, "%s", nasm_reg_names[reg-EXPR_REG_START]); } else if (!(UNITY & ~t)) { output[slen++] = '1'; } else if (t & IMMEDIATE) { if (t & BITS8) { slen += snprintf(output + slen, outbufsize - slen, "byte "); if (o->segment & SEG_SIGNED) { if (offs < 0) { offs *= -1; output[slen++] = '-'; } else output[slen++] = '+'; } } else if (t & BITS16) { slen += snprintf(output + slen, outbufsize - slen, "word "); } else if (t & BITS32) { slen += snprintf(output + slen, outbufsize - slen, "dword "); } else if (t & BITS64) { slen += snprintf(output + slen, outbufsize - slen, "qword "); } else if (t & NEAR) { slen += snprintf(output + slen, outbufsize - slen, "near "); } else if (t & SHORT) { slen += snprintf(output + slen, outbufsize - slen, "short "); } slen += snprintf(output + slen, outbufsize - slen, "0x%"PRIx64"", offs); } else if (!(MEM_OFFS & ~t)) { slen += snprintf(output + slen, outbufsize - slen, "[%s%s%s0x%"PRIx64"]", (segover ? segover : ""), (segover ? ":" : ""), (o->disp_size == 64 ? "qword " : o->disp_size == 32 ? "dword " : o->disp_size == 16 ? "word " : ""), offs); segover = NULL; } else if (!(REGMEM & ~t)) { int started = false; if (t & BITS8) slen += snprintf(output + slen, outbufsize - slen, "byte "); if (t & BITS16) slen += snprintf(output + slen, outbufsize - slen, "word "); if (t & BITS32) slen += snprintf(output + slen, outbufsize - slen, "dword "); if (t & BITS64) slen += snprintf(output + slen, outbufsize - slen, "qword "); if (t & BITS80) slen += snprintf(output + slen, outbufsize - slen, "tword "); if (t & BITS128) slen += snprintf(output + slen, outbufsize - slen, "oword "); if (t & BITS256) slen += snprintf(output + slen, outbufsize - slen, "yword "); if (t & FAR) slen += snprintf(output + slen, outbufsize - slen, "far "); if (t & NEAR) slen += snprintf(output + slen, outbufsize - slen, "near "); output[slen++] = '['; if (o->disp_size) slen += snprintf(output + slen, outbufsize - slen, "%s", (o->disp_size == 64 ? "qword " : o->disp_size == 32 ? "dword " : o->disp_size == 16 ? "word " : "")); if (o->eaflags & EAF_REL) slen += snprintf(output + slen, outbufsize - slen, "rel "); if (segover) { slen += snprintf(output + slen, outbufsize - slen, "%s:", segover); segover = NULL; } if (o->basereg != -1) { slen += snprintf(output + slen, outbufsize - slen, "%s", nasm_reg_names[(o->basereg-EXPR_REG_START)]); started = true; } if (o->indexreg != -1) { if (started) output[slen++] = '+'; slen += snprintf(output + slen, outbufsize - slen, "%s", nasm_reg_names[(o->indexreg-EXPR_REG_START)]); if (o->scale > 1) slen += snprintf(output + slen, outbufsize - slen, "*%d", o->scale); started = true; } if (o->segment & SEG_DISP8) { const char *prefix; uint8_t offset = offs; if ((int8_t)offset < 0) { prefix = "-"; offset = -offset; } else { prefix = "+"; } slen += snprintf(output + slen, outbufsize - slen, "%s0x%"PRIx8"", prefix, offset); } else if (o->segment & SEG_DISP16) { const char *prefix; uint16_t offset = offs; if ((int16_t)offset < 0 && started) { offset = -offset; prefix = "-"; } else { prefix = started ? "+" : ""; } slen += snprintf(output + slen, outbufsize - slen, "%s0x%"PRIx16"", prefix, offset); } else if (o->segment & SEG_DISP32) { if (prefix.asize == 64) { const char *prefix; uint64_t offset = (int64_t)(int32_t)offs; if ((int32_t)offs < 0 && started) { offset = -offset; prefix = "-"; } else { prefix = started ? "+" : ""; } slen += snprintf(output + slen, outbufsize - slen, "%s0x%"PRIx64"", prefix, offset); } else { const char *prefix; uint32_t offset = offs; if ((int32_t) offset < 0 && started) { offset = -offset; prefix = "-"; } else { prefix = started ? "+" : ""; } slen += snprintf(output + slen, outbufsize - slen, "%s0x%"PRIx32"", prefix, offset); } } output[slen++] = ']'; } else { slen += snprintf(output + slen, outbufsize - slen, "", i); } } output[slen] = '\0'; if (segover) { /* unused segment override */ char *p = output; int count = slen + 1; while (count--) p[count + 3] = p[count]; strncpy(output, segover, 2); output[2] = ' '; } return length; } int32_t eatbyte(uint8_t *data, char *output, int outbufsize) { snprintf(output, outbufsize, "db 0x%02X", *data); return 1; }