/*
 * This file is part of the MicroPython project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2016 Damien P. George
 * Copyright (c) Quectel Wireless Solution, Co., Ltd.All Rights Reserved.
 *
 * 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 <stdio.h>
#include <assert.h>

#include "py/mpconfig.h"

// wrapper around everything in this file
#if MICROPY_EMIT_XTENSA || MICROPY_EMIT_INLINE_XTENSA || MICROPY_EMIT_XTENSAWIN

#include "py/asmxtensa.h"

#define WORD_SIZE (4)
#define SIGNED_FIT8(x) ((((x) & 0xffffff80) == 0) || (((x) & 0xffffff80) == 0xffffff80))
#define SIGNED_FIT12(x) ((((x) & 0xfffff800) == 0) || (((x) & 0xfffff800) == 0xfffff800))

void asm_xtensa_end_pass(asm_xtensa_t *as) {
 as->num_const = as->cur_const;
 as->cur_const = 0;

 #if 0
 // make a hex dump of the machine code
 if (as->base.pass == MP_ASM_PASS_EMIT) {
 uint8_t *d = as->base.code_base;
 printf("XTENSA ASM:");
 for (int i = 0; i < ((as->base.code_size + 15) & ~15); ++i) {
 if (i % 16 == 0) {
 printf("\n%08x:", (uint32_t)&d[i]);
 }
 if (i % 2 == 0) {
 printf(" ");
 }
 printf("%02x", d[i]);
 }
 printf("\n");
 }
 #endif
}

void asm_xtensa_entry(asm_xtensa_t *as, int num_locals) {
 // jump over the constants
 asm_xtensa_op_j(as, as->num_const * WORD_SIZE + 4 - 4);
 mp_asm_base_get_cur_to_write_bytes(&as->base, 1); // padding/alignment byte
 as->const_table = (uint32_t *)mp_asm_base_get_cur_to_write_bytes(&as->base, as->num_const * 4);

 // adjust the stack-pointer to store a0, a12, a13, a14, a15 and locals, 16-byte aligned
 as->stack_adjust = (((ASM_XTENSA_NUM_REGS_SAVED + num_locals) * WORD_SIZE) + 15) & ~15;
 if (SIGNED_FIT8(-as->stack_adjust)) {
 asm_xtensa_op_addi(as, ASM_XTENSA_REG_A1, ASM_XTENSA_REG_A1, -as->stack_adjust);
 } else {
 asm_xtensa_op_movi(as, ASM_XTENSA_REG_A9, as->stack_adjust);
 asm_xtensa_op_sub(as, ASM_XTENSA_REG_A1, ASM_XTENSA_REG_A1, ASM_XTENSA_REG_A9);
 }

 // save return value (a0) and callee-save registers (a12, a13, a14, a15)
 asm_xtensa_op_s32i_n(as, ASM_XTENSA_REG_A0, ASM_XTENSA_REG_A1, 0);
 for (int i = 1; i < ASM_XTENSA_NUM_REGS_SAVED; ++i) {
 asm_xtensa_op_s32i_n(as, ASM_XTENSA_REG_A11 + i, ASM_XTENSA_REG_A1, i);
 }
}

void asm_xtensa_exit(asm_xtensa_t *as) {
 // restore registers
 for (int i = ASM_XTENSA_NUM_REGS_SAVED - 1; i >= 1; --i) {
 asm_xtensa_op_l32i_n(as, ASM_XTENSA_REG_A11 + i, ASM_XTENSA_REG_A1, i);
 }
 asm_xtensa_op_l32i_n(as, ASM_XTENSA_REG_A0, ASM_XTENSA_REG_A1, 0);

 // restore stack-pointer and return
 if (SIGNED_FIT8(as->stack_adjust)) {
 asm_xtensa_op_addi(as, ASM_XTENSA_REG_A1, ASM_XTENSA_REG_A1, as->stack_adjust);
 } else {
 asm_xtensa_op_movi(as, ASM_XTENSA_REG_A9, as->stack_adjust);
 asm_xtensa_op_add_n(as, ASM_XTENSA_REG_A1, ASM_XTENSA_REG_A1, ASM_XTENSA_REG_A9);
 }

 asm_xtensa_op_ret_n(as);
}

void asm_xtensa_entry_win(asm_xtensa_t *as, int num_locals) {
 // jump over the constants
 asm_xtensa_op_j(as, as->num_const * WORD_SIZE + 4 - 4);
 mp_asm_base_get_cur_to_write_bytes(&as->base, 1); // padding/alignment byte
 as->const_table = (uint32_t *)mp_asm_base_get_cur_to_write_bytes(&as->base, as->num_const * 4);

 as->stack_adjust = 32 + ((((ASM_XTENSA_NUM_REGS_SAVED_WIN + num_locals) * WORD_SIZE) + 15) & ~15);
 asm_xtensa_op_entry(as, ASM_XTENSA_REG_A1, as->stack_adjust);
 asm_xtensa_op_s32i_n(as, ASM_XTENSA_REG_A0, ASM_XTENSA_REG_A1, 0);
}

void asm_xtensa_exit_win(asm_xtensa_t *as) {
 asm_xtensa_op_l32i_n(as, ASM_XTENSA_REG_A0, ASM_XTENSA_REG_A1, 0);
 asm_xtensa_op_retw_n(as);
}

STATIC uint32_t get_label_dest(asm_xtensa_t *as, uint label) {
 assert(label < as->base.max_num_labels);
 return as->base.label_offsets[label];
}

void asm_xtensa_op16(asm_xtensa_t *as, uint16_t op) {
 uint8_t *c = mp_asm_base_get_cur_to_write_bytes(&as->base, 2);
 if (c != NULL) {
 c[0] = op;
 c[1] = op >> 8;
 }
}

void asm_xtensa_op24(asm_xtensa_t *as, uint32_t op) {
 uint8_t *c = mp_asm_base_get_cur_to_write_bytes(&as->base, 3);
 if (c != NULL) {
 c[0] = op;
 c[1] = op >> 8;
 c[2] = op >> 16;
 }
}

void asm_xtensa_j_label(asm_xtensa_t *as, uint label) {
 uint32_t dest = get_label_dest(as, label);
 int32_t rel = dest - as->base.code_offset - 4;
 // we assume rel, as a signed int, fits in 18-bits
 asm_xtensa_op_j(as, rel);
}

void asm_xtensa_bccz_reg_label(asm_xtensa_t *as, uint cond, uint reg, uint label) {
 uint32_t dest = get_label_dest(as, label);
 int32_t rel = dest - as->base.code_offset - 4;
 if (as->base.pass == MP_ASM_PASS_EMIT && !SIGNED_FIT12(rel)) {
 printf("ERROR: xtensa bccz out of range\n");
 }
 asm_xtensa_op_bccz(as, cond, reg, rel);
}

void asm_xtensa_bcc_reg_reg_label(asm_xtensa_t *as, uint cond, uint reg1, uint reg2, uint label) {
 uint32_t dest = get_label_dest(as, label);
 int32_t rel = dest - as->base.code_offset - 4;
 if (as->base.pass == MP_ASM_PASS_EMIT && !SIGNED_FIT8(rel)) {
 printf("ERROR: xtensa bcc out of range\n");
 }
 asm_xtensa_op_bcc(as, cond, reg1, reg2, rel);
}

// convenience function; reg_dest must be different from reg_src[12]
void asm_xtensa_setcc_reg_reg_reg(asm_xtensa_t *as, uint cond, uint reg_dest, uint reg_src1, uint reg_src2) {
 asm_xtensa_op_movi_n(as, reg_dest, 1);
 asm_xtensa_op_bcc(as, cond, reg_src1, reg_src2, 1);
 asm_xtensa_op_movi_n(as, reg_dest, 0);
}

size_t asm_xtensa_mov_reg_i32(asm_xtensa_t *as, uint reg_dest, uint32_t i32) {
 // load the constant
 uint32_t const_table_offset = (uint8_t *)as->const_table - as->base.code_base;
 size_t loc = const_table_offset + as->cur_const * WORD_SIZE;
 asm_xtensa_op_l32r(as, reg_dest, as->base.code_offset, loc);
 // store the constant in the table
 if (as->const_table != NULL) {
 as->const_table[as->cur_const] = i32;
 }
 ++as->cur_const;
 return loc;
}

void asm_xtensa_mov_reg_i32_optimised(asm_xtensa_t *as, uint reg_dest, uint32_t i32) {
 if (SIGNED_FIT12(i32)) {
 asm_xtensa_op_movi(as, reg_dest, i32);
 } else {
 asm_xtensa_mov_reg_i32(as, reg_dest, i32);
 }
}

void asm_xtensa_mov_local_reg(asm_xtensa_t *as, int local_num, uint reg_src) {
 asm_xtensa_op_s32i(as, reg_src, ASM_XTENSA_REG_A1, local_num);
}

void asm_xtensa_mov_reg_local(asm_xtensa_t *as, uint reg_dest, int local_num) {
 asm_xtensa_op_l32i(as, reg_dest, ASM_XTENSA_REG_A1, local_num);
}

void asm_xtensa_mov_reg_local_addr(asm_xtensa_t *as, uint reg_dest, int local_num) {
 uint off = local_num * WORD_SIZE;
 if (SIGNED_FIT8(off)) {
 asm_xtensa_op_addi(as, reg_dest, ASM_XTENSA_REG_A1, off);
 } else {
 asm_xtensa_op_movi(as, reg_dest, off);
 asm_xtensa_op_add_n(as, reg_dest, reg_dest, ASM_XTENSA_REG_A1);
 }
}

void asm_xtensa_mov_reg_pcrel(asm_xtensa_t *as, uint reg_dest, uint label) {
 // Get relative offset from PC
 uint32_t dest = get_label_dest(as, label);
 int32_t rel = dest - as->base.code_offset;
 rel -= 3 + 3; // account for 3 bytes of movi instruction, 3 bytes call0 adjustment
 asm_xtensa_op_movi(as, reg_dest, rel); // imm has 12-bit range

 // Use call0 to get PC+3 into a0
 // call0 destination must be aligned on 4 bytes:
 // - code_offset&3=0: off=0, pad=1
 // - code_offset&3=1: off=0, pad=0
 // - code_offset&3=2: off=1, pad=3
 // - code_offset&3=3: off=1, pad=2
 uint32_t off = as->base.code_offset >> 1 & 1;
 uint32_t pad = (5 - as->base.code_offset) & 3;
 asm_xtensa_op_call0(as, off);
 mp_asm_base_get_cur_to_write_bytes(&as->base, pad);

 // Add PC to relative offset
 asm_xtensa_op_add_n(as, reg_dest, reg_dest, ASM_XTENSA_REG_A0);
}

void asm_xtensa_call_ind(asm_xtensa_t *as, uint idx) {
 if (idx < 16) {
 asm_xtensa_op_l32i_n(as, ASM_XTENSA_REG_A0, ASM_XTENSA_REG_FUN_TABLE, idx);
 } else {
 asm_xtensa_op_l32i(as, ASM_XTENSA_REG_A0, ASM_XTENSA_REG_FUN_TABLE, idx);
 }
 asm_xtensa_op_callx0(as, ASM_XTENSA_REG_A0);
}

void asm_xtensa_call_ind_win(asm_xtensa_t *as, uint idx) {
 if (idx < 16) {
 asm_xtensa_op_l32i_n(as, ASM_XTENSA_REG_A8, ASM_XTENSA_REG_FUN_TABLE_WIN, idx);
 } else {
 asm_xtensa_op_l32i(as, ASM_XTENSA_REG_A8, ASM_XTENSA_REG_FUN_TABLE_WIN, idx);
 }
 asm_xtensa_op_callx8(as, ASM_XTENSA_REG_A8);
}

#endif // MICROPY_EMIT_XTENSA || MICROPY_EMIT_INLINE_XTENSA || MICROPY_EMIT_XTENSAWIN