/*
   * This file is part of the MicroPython project, http://micropython.org/
   *
   * The MIT License (MIT)
   *
   * Copyright (c) 2013-2016 Damien P. George
   *
   * Permission is hereby granted, free of charge, to any person obtaining a copy
   * of this software and associated documentation files (the "Software"), to deal
   * in the Software without restriction, including without limitation the rights
   * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   * copies of the Software, and to permit persons to whom the Software is
   * furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in
   * all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
   * THE SOFTWARE.
   */
  
  #include <stdint.h>
  #include <stdio.h>
  #include <string.h>
  #include <stdarg.h>
  #include <assert.h>
  
  #include "py/emit.h"
  #include "py/asmxtensa.h"
  
  #if MICROPY_EMIT_INLINE_XTENSA
  
  struct _emit_inline_asm_t {
      asm_xtensa_t as;
      uint16_t pass;
      mp_obj_t *error_slot;
      mp_uint_t max_num_labels;
      qstr *label_lookup;
  };
  
  STATIC void emit_inline_xtensa_error_msg(emit_inline_asm_t *emit, const char *msg) {
      *emit->error_slot = mp_obj_new_exception_msg(&mp_type_SyntaxError, msg);
  }
  
  STATIC void emit_inline_xtensa_error_exc(emit_inline_asm_t *emit, mp_obj_t exc) {
      *emit->error_slot = exc;
  }
  
  emit_inline_asm_t *emit_inline_xtensa_new(mp_uint_t max_num_labels) {
      emit_inline_asm_t *emit = m_new_obj(emit_inline_asm_t);
      memset(&emit->as, 0, sizeof(emit->as));
      mp_asm_base_init(&emit->as.base, max_num_labels);
      emit->max_num_labels = max_num_labels;
      emit->label_lookup = m_new(qstr, max_num_labels);
      return emit;
  }
  
  void emit_inline_xtensa_free(emit_inline_asm_t *emit) {
      m_del(qstr, emit->label_lookup, emit->max_num_labels);
      mp_asm_base_deinit(&emit->as.base, false);
      m_del_obj(emit_inline_asm_t, emit);
  }
  
  STATIC void emit_inline_xtensa_start_pass(emit_inline_asm_t *emit, pass_kind_t pass, mp_obj_t *error_slot) {
      emit->pass = pass;
      emit->error_slot = error_slot;
      if (emit->pass == MP_PASS_CODE_SIZE) {
          memset(emit->label_lookup, 0, emit->max_num_labels * sizeof(qstr));
      }
      mp_asm_base_start_pass(&emit->as.base, pass == MP_PASS_EMIT ? MP_ASM_PASS_EMIT : MP_ASM_PASS_COMPUTE);
      asm_xtensa_entry(&emit->as, 0);
  }
  
  STATIC void emit_inline_xtensa_end_pass(emit_inline_asm_t *emit, mp_uint_t type_sig) {
      asm_xtensa_exit(&emit->as);
      asm_xtensa_end_pass(&emit->as);
  }
  
  STATIC mp_uint_t emit_inline_xtensa_count_params(emit_inline_asm_t *emit, mp_uint_t n_params, mp_parse_node_t *pn_params) {
      if (n_params > 4) {
          emit_inline_xtensa_error_msg(emit, "can only have up to 4 parameters to Xtensa assembly");
          return 0;
      }
      for (mp_uint_t i = 0; i < n_params; i++) {
          if (!MP_PARSE_NODE_IS_ID(pn_params[i])) {
              emit_inline_xtensa_error_msg(emit, "parameters must be registers in sequence a2 to a5");
              return 0;
          }
          const char *p = qstr_str(MP_PARSE_NODE_LEAF_ARG(pn_params[i]));
          if (!(strlen(p) == 2 && p[0] == 'a' && p[1] == '2' + i)) {
              emit_inline_xtensa_error_msg(emit, "parameters must be registers in sequence a2 to a5");
              return 0;
          }
      }
      return n_params;
  }
  
  STATIC bool emit_inline_xtensa_label(emit_inline_asm_t *emit, mp_uint_t label_num, qstr label_id) {
      assert(label_num < emit->max_num_labels);
      if (emit->pass == MP_PASS_CODE_SIZE) {
          // check for duplicate label on first pass
          for (uint i = 0; i < emit->max_num_labels; i++) {
              if (emit->label_lookup[i] == label_id) {
                  return false;
              }
          }
      }
      emit->label_lookup[label_num] = label_id;
      mp_asm_base_label_assign(&emit->as.base, label_num);
      return true;
  }
  
  typedef struct _reg_name_t { byte reg; byte name[3]; } reg_name_t;
  STATIC const reg_name_t reg_name_table[] = {
      {0, "a0\0"},
      {1, "a1\0"},
      {2, "a2\0"},
      {3, "a3\0"},
      {4, "a4\0"},
      {5, "a5\0"},
      {6, "a6\0"},
      {7, "a7\0"},
      {8, "a8\0"},
      {9, "a9\0"},
      {10, "a10"},
      {11, "a11"},
      {12, "a12"},
      {13, "a13"},
      {14, "a14"},
      {15, "a15"},
  };
  
  // return empty string in case of error, so we can attempt to parse the string
  // without a special check if it was in fact a string
  STATIC const char *get_arg_str(mp_parse_node_t pn) {
      if (MP_PARSE_NODE_IS_ID(pn)) {
          qstr qst = MP_PARSE_NODE_LEAF_ARG(pn);
          return qstr_str(qst);
      } else {
          return "";
      }
  }
  
  STATIC mp_uint_t get_arg_reg(emit_inline_asm_t *emit, const char *op, mp_parse_node_t pn) {
      const char *reg_str = get_arg_str(pn);
      for (mp_uint_t i = 0; i < MP_ARRAY_SIZE(reg_name_table); i++) {
          const reg_name_t *r = &reg_name_table[i];
          if (reg_str[0] == r->name[0]
              && reg_str[1] == r->name[1]
              && reg_str[2] == r->name[2]
              && (reg_str[2] == '\0' || reg_str[3] == '\0')) {
              return r->reg;
          }
      }
      emit_inline_xtensa_error_exc(emit,
          mp_obj_new_exception_msg_varg(&mp_type_SyntaxError,
              "'%s' expects a register", op));
      return 0;
  }
  
  STATIC uint32_t get_arg_i(emit_inline_asm_t *emit, const char *op, mp_parse_node_t pn, int min, int max) {
      mp_obj_t o;
      if (!mp_parse_node_get_int_maybe(pn, &o)) {
          emit_inline_xtensa_error_exc(emit, mp_obj_new_exception_msg_varg(&mp_type_SyntaxError, "'%s' expects an integer", op));
          return 0;
      }
      uint32_t i = mp_obj_get_int_truncated(o);
      if (min != max && ((int)i < min || (int)i > max)) {
          emit_inline_xtensa_error_exc(emit, mp_obj_new_exception_msg_varg(&mp_type_SyntaxError, "'%s' integer %d is not within range %d..%d", op, i, min, max));
          return 0;
      }
      return i;
  }
  
  STATIC int get_arg_label(emit_inline_asm_t *emit, const char *op, mp_parse_node_t pn) {
      if (!MP_PARSE_NODE_IS_ID(pn)) {
          emit_inline_xtensa_error_exc(emit, mp_obj_new_exception_msg_varg(&mp_type_SyntaxError, "'%s' expects a label", op));
          return 0;
      }
      qstr label_qstr = MP_PARSE_NODE_LEAF_ARG(pn);
      for (uint i = 0; i < emit->max_num_labels; i++) {
          if (emit->label_lookup[i] == label_qstr) {
              return i;
          }
      }
      // only need to have the labels on the last pass
      if (emit->pass == MP_PASS_EMIT) {
          emit_inline_xtensa_error_exc(emit, mp_obj_new_exception_msg_varg(&mp_type_SyntaxError, "label '%q' not defined", label_qstr));
      }
      return 0;
  }
  
  #define RRR (0)
  #define RRI8 (1)
  #define RRI8_B (2)
  
  typedef struct _opcode_table_3arg_t {
      uint16_t name; // actually a qstr, which should fit in 16 bits
      uint8_t type;
      uint8_t a0 : 4;
      uint8_t a1 : 4;
  } opcode_table_3arg_t;
  
  STATIC const opcode_table_3arg_t opcode_table_3arg[] = {
      // arithmetic opcodes: reg, reg, reg
      {MP_QSTR_and_, RRR, 0, 1},
      {MP_QSTR_or_, RRR, 0, 2},
      {MP_QSTR_xor, RRR, 0, 3},
      {MP_QSTR_add, RRR, 0, 8},
      {MP_QSTR_sub, RRR, 0, 12},
      {MP_QSTR_mull, RRR, 2, 8},
  
      // load/store/addi opcodes: reg, reg, imm
      // upper nibble of type encodes the range of the immediate arg
      {MP_QSTR_l8ui, RRI8 | 0x10, 2, 0},
      {MP_QSTR_l16ui, RRI8 | 0x30, 2, 1},
      {MP_QSTR_l32i, RRI8 | 0x50, 2, 2},
      {MP_QSTR_s8i, RRI8 | 0x10, 2, 4},
      {MP_QSTR_s16i, RRI8 | 0x30, 2, 5},
      {MP_QSTR_s32i, RRI8 | 0x50, 2, 6},
      {MP_QSTR_l16si, RRI8 | 0x30, 2, 9},
      {MP_QSTR_addi, RRI8 | 0x00, 2, 12},
  
      // branch opcodes: reg, reg, label
      {MP_QSTR_ball, RRI8_B, ASM_XTENSA_CC_ALL, 0},
      {MP_QSTR_bany, RRI8_B, ASM_XTENSA_CC_ANY, 0},
      {MP_QSTR_bbc, RRI8_B, ASM_XTENSA_CC_BC, 0},
      {MP_QSTR_bbs, RRI8_B, ASM_XTENSA_CC_BS, 0},
      {MP_QSTR_beq, RRI8_B, ASM_XTENSA_CC_EQ, 0},
      {MP_QSTR_bge, RRI8_B, ASM_XTENSA_CC_GE, 0},
      {MP_QSTR_bgeu, RRI8_B, ASM_XTENSA_CC_GEU, 0},
      {MP_QSTR_blt, RRI8_B, ASM_XTENSA_CC_LT, 0},
      {MP_QSTR_bnall, RRI8_B, ASM_XTENSA_CC_NALL, 0},
      {MP_QSTR_bne, RRI8_B, ASM_XTENSA_CC_NE, 0},
      {MP_QSTR_bnone, RRI8_B, ASM_XTENSA_CC_NONE, 0},
  };
  
  STATIC void emit_inline_xtensa_op(emit_inline_asm_t *emit, qstr op, mp_uint_t n_args, mp_parse_node_t *pn_args) {
      size_t op_len;
      const char *op_str = (const char*)qstr_data(op, &op_len);
  
      if (n_args == 0) {
          if (op == MP_QSTR_ret_n) {
              asm_xtensa_op_ret_n(&emit->as);
          } else {
              goto unknown_op;
          }
  
      } else if (n_args == 1) {
          if (op == MP_QSTR_callx0) {
              uint r0 = get_arg_reg(emit, op_str, pn_args[0]);
              asm_xtensa_op_callx0(&emit->as, r0);
          } else if (op == MP_QSTR_j) {
              int label = get_arg_label(emit, op_str, pn_args[0]);
              asm_xtensa_j_label(&emit->as, label);
          } else if (op == MP_QSTR_jx) {
              uint r0 = get_arg_reg(emit, op_str, pn_args[0]);
              asm_xtensa_op_jx(&emit->as, r0);
          } else {
              goto unknown_op;
          }
  
      } else if (n_args == 2) {
          uint r0 = get_arg_reg(emit, op_str, pn_args[0]);
          if (op == MP_QSTR_beqz) {
              int label = get_arg_label(emit, op_str, pn_args[1]);
              asm_xtensa_bccz_reg_label(&emit->as, ASM_XTENSA_CCZ_EQ, r0, label);
          } else if (op == MP_QSTR_bnez) {
              int label = get_arg_label(emit, op_str, pn_args[1]);
              asm_xtensa_bccz_reg_label(&emit->as, ASM_XTENSA_CCZ_NE, r0, label);
          } else if (op == MP_QSTR_mov || op == MP_QSTR_mov_n) {
              // we emit mov.n for both "mov" and "mov_n" opcodes
              uint r1 = get_arg_reg(emit, op_str, pn_args[1]);
              asm_xtensa_op_mov_n(&emit->as, r0, r1);
          } else if (op == MP_QSTR_movi) {
              // for convenience we emit l32r if the integer doesn't fit in movi
              uint32_t imm = get_arg_i(emit, op_str, pn_args[1], 0, 0);
              asm_xtensa_mov_reg_i32(&emit->as, r0, imm);
          } else {
              goto unknown_op;
          }
  
      } else if (n_args == 3) {
          // search table for 3 arg instructions
          for (uint i = 0; i < MP_ARRAY_SIZE(opcode_table_3arg); i++) {
              const opcode_table_3arg_t *o = &opcode_table_3arg[i];
              if (op == o->name) {
                  uint r0 = get_arg_reg(emit, op_str, pn_args[0]);
                  uint r1 = get_arg_reg(emit, op_str, pn_args[1]);
                  if (o->type == RRR) {
                      uint r2 = get_arg_reg(emit, op_str, pn_args[2]);
                      asm_xtensa_op24(&emit->as, ASM_XTENSA_ENCODE_RRR(0, o->a0, o->a1, r0, r1, r2));
                  } else if (o->type == RRI8_B) {
                      int label = get_arg_label(emit, op_str, pn_args[2]);
                      asm_xtensa_bcc_reg_reg_label(&emit->as, o->a0, r0, r1, label);
                  } else {
                      int shift, min, max;
                      if ((o->type & 0xf0) == 0) {
                          shift = 0;
                          min = -128;
                          max = 127;
                      } else {
                          shift = (o->type & 0xf0) >> 5;
                          min = 0;
                          max = 0xff << shift;
                      }
                      uint32_t imm = get_arg_i(emit, op_str, pn_args[2], min, max);
                      asm_xtensa_op24(&emit->as, ASM_XTENSA_ENCODE_RRI8(o->a0, o->a1, r1, r0, (imm >> shift) & 0xff));
                  }
                  return;
              }
          }
          goto unknown_op;
  
      } else {
          goto unknown_op;
      }
  
      return;
  
  unknown_op:
      emit_inline_xtensa_error_exc(emit, mp_obj_new_exception_msg_varg(&mp_type_SyntaxError, "unsupported Xtensa instruction '%s' with %d arguments", op_str, n_args));
      return;
  
      /*
  branch_not_in_range:
      emit_inline_xtensa_error_msg(emit, "branch not in range");
      return;
      */
  }
  
  const emit_inline_asm_method_table_t emit_inline_xtensa_method_table = {
      emit_inline_xtensa_start_pass,
      emit_inline_xtensa_end_pass,
      emit_inline_xtensa_count_params,
      emit_inline_xtensa_label,
      emit_inline_xtensa_op,
  };
  
  #endif // MICROPY_EMIT_INLINE_XTENSA