diff options
| -rw-r--r-- | py/asmx86.c | 67 |
1 files changed, 40 insertions, 27 deletions
diff --git a/py/asmx86.c b/py/asmx86.c index 942b83fb1..81ff1d00d 100644 --- a/py/asmx86.c +++ b/py/asmx86.c @@ -137,14 +137,22 @@ STATIC void asm_x86_write_word32(asm_x86_t *as, int w32) { } STATIC void asm_x86_write_r32_disp(asm_x86_t *as, int r32, int disp_r32, int disp_offset) { - assert(disp_r32 != ASM_X86_REG_ESP); - + uint8_t rm_disp; if (disp_offset == 0 && disp_r32 != ASM_X86_REG_EBP) { - asm_x86_write_byte_1(as, MODRM_R32(r32) | MODRM_RM_DISP0 | MODRM_RM_R32(disp_r32)); + rm_disp = MODRM_RM_DISP0; } else if (SIGNED_FIT8(disp_offset)) { - asm_x86_write_byte_2(as, MODRM_R32(r32) | MODRM_RM_DISP8 | MODRM_RM_R32(disp_r32), IMM32_L0(disp_offset)); + rm_disp = MODRM_RM_DISP8; } else { - asm_x86_write_byte_1(as, MODRM_R32(r32) | MODRM_RM_DISP32 | MODRM_RM_R32(disp_r32)); + rm_disp = MODRM_RM_DISP32; + } + asm_x86_write_byte_1(as, MODRM_R32(r32) | rm_disp | MODRM_RM_R32(disp_r32)); + if (disp_r32 == ASM_X86_REG_ESP) { + // Special case for esp, it needs a SIB byte + asm_x86_write_byte_1(as, 0x24); + } + if (rm_disp == MODRM_RM_DISP8) { + asm_x86_write_byte_1(as, IMM32_L0(disp_offset)); + } else if (rm_disp == MODRM_RM_DISP32) { asm_x86_write_word32(as, disp_offset); } } @@ -390,70 +398,75 @@ void asm_x86_jcc_label(asm_x86_t *as, mp_uint_t jcc_type, mp_uint_t label) { void asm_x86_entry(asm_x86_t *as, int num_locals) { assert(num_locals >= 0); asm_x86_push_r32(as, ASM_X86_REG_EBP); - asm_x86_mov_r32_r32(as, ASM_X86_REG_EBP, ASM_X86_REG_ESP); - if (num_locals > 0) { - asm_x86_sub_r32_i32(as, ASM_X86_REG_ESP, num_locals * WORD_SIZE); - } asm_x86_push_r32(as, ASM_X86_REG_EBX); asm_x86_push_r32(as, ASM_X86_REG_ESI); asm_x86_push_r32(as, ASM_X86_REG_EDI); - // TODO align stack on 16-byte boundary + num_locals |= 1; // make it odd so stack is aligned on 16 byte boundary + asm_x86_sub_r32_i32(as, ASM_X86_REG_ESP, num_locals * WORD_SIZE); as->num_locals = num_locals; } void asm_x86_exit(asm_x86_t *as) { + asm_x86_sub_r32_i32(as, ASM_X86_REG_ESP, -as->num_locals * WORD_SIZE); asm_x86_pop_r32(as, ASM_X86_REG_EDI); asm_x86_pop_r32(as, ASM_X86_REG_ESI); asm_x86_pop_r32(as, ASM_X86_REG_EBX); - asm_x86_write_byte_1(as, OPCODE_LEAVE); + asm_x86_pop_r32(as, ASM_X86_REG_EBP); asm_x86_ret(as); } +STATIC int asm_x86_arg_offset_from_esp(asm_x86_t *as, size_t arg_num) { + // Above esp are: locals, 4 saved registers, return eip, arguments + return (as->num_locals + 4 + 1 + arg_num) * WORD_SIZE; +} + #if 0 void asm_x86_push_arg(asm_x86_t *as, int src_arg_num) { - asm_x86_push_disp(as, ASM_X86_REG_EBP, 2 * WORD_SIZE + src_arg_num * WORD_SIZE); + asm_x86_push_disp(as, ASM_X86_REG_ESP, asm_x86_arg_offset_from_esp(as, src_arg_num)); } #endif void asm_x86_mov_arg_to_r32(asm_x86_t *as, int src_arg_num, int dest_r32) { - asm_x86_mov_mem32_to_r32(as, ASM_X86_REG_EBP, 2 * WORD_SIZE + src_arg_num * WORD_SIZE, dest_r32); + asm_x86_mov_mem32_to_r32(as, ASM_X86_REG_ESP, asm_x86_arg_offset_from_esp(as, src_arg_num), dest_r32); } #if 0 void asm_x86_mov_r32_to_arg(asm_x86_t *as, int src_r32, int dest_arg_num) { - asm_x86_mov_r32_to_mem32(as, src_r32, ASM_X86_REG_EBP, 2 * WORD_SIZE + dest_arg_num * WORD_SIZE); + asm_x86_mov_r32_to_mem32(as, src_r32, ASM_X86_REG_ESP, asm_x86_arg_offset_from_esp(as, dest_arg_num)); } #endif // locals: // - stored on the stack in ascending order // - numbered 0 through as->num_locals-1 -// - EBP points above the last local +// - ESP points to the first local // -// | EBP -// v +// | ESP +// v // l0 l1 l2 ... l(n-1) // ^ ^ // | low address | high address in RAM // -STATIC int asm_x86_local_offset_from_ebp(asm_x86_t *as, int local_num) { - return (-as->num_locals + local_num) * WORD_SIZE; +STATIC int asm_x86_local_offset_from_esp(asm_x86_t *as, int local_num) { + (void)as; + // Stack is full descending, ESP points to local0 + return local_num * WORD_SIZE; } void asm_x86_mov_local_to_r32(asm_x86_t *as, int src_local_num, int dest_r32) { - asm_x86_mov_mem32_to_r32(as, ASM_X86_REG_EBP, asm_x86_local_offset_from_ebp(as, src_local_num), dest_r32); + asm_x86_mov_mem32_to_r32(as, ASM_X86_REG_ESP, asm_x86_local_offset_from_esp(as, src_local_num), dest_r32); } void asm_x86_mov_r32_to_local(asm_x86_t *as, int src_r32, int dest_local_num) { - asm_x86_mov_r32_to_mem32(as, src_r32, ASM_X86_REG_EBP, asm_x86_local_offset_from_ebp(as, dest_local_num)); + asm_x86_mov_r32_to_mem32(as, src_r32, ASM_X86_REG_ESP, asm_x86_local_offset_from_esp(as, dest_local_num)); } void asm_x86_mov_local_addr_to_r32(asm_x86_t *as, int local_num, int dest_r32) { - int offset = asm_x86_local_offset_from_ebp(as, local_num); + int offset = asm_x86_local_offset_from_esp(as, local_num); if (offset == 0) { - asm_x86_mov_r32_r32(as, dest_r32, ASM_X86_REG_EBP); + asm_x86_mov_r32_r32(as, dest_r32, ASM_X86_REG_ESP); } else { - asm_x86_lea_disp_to_r32(as, ASM_X86_REG_EBP, offset, dest_r32); + asm_x86_lea_disp_to_r32(as, ASM_X86_REG_ESP, offset, dest_r32); } } @@ -470,13 +483,13 @@ void asm_x86_mov_reg_pcrel(asm_x86_t *as, int dest_r32, mp_uint_t label) { #if 0 void asm_x86_push_local(asm_x86_t *as, int local_num) { - asm_x86_push_disp(as, ASM_X86_REG_EBP, asm_x86_local_offset_from_ebp(as, local_num)); + asm_x86_push_disp(as, ASM_X86_REG_ESP, asm_x86_local_offset_from_esp(as, local_num)); } void asm_x86_push_local_addr(asm_x86_t *as, int local_num, int temp_r32) { - asm_x86_mov_r32_r32(as, temp_r32, ASM_X86_REG_EBP); - asm_x86_add_i32_to_r32(as, asm_x86_local_offset_from_ebp(as, local_num), temp_r32); + asm_x86_mov_r32_r32(as, temp_r32, ASM_X86_REG_ESP); + asm_x86_add_i32_to_r32(as, asm_x86_local_offset_from_esp(as, local_num), temp_r32); asm_x86_push_r32(as, temp_r32); } #endif |