# This Source Code Form is subject to the terms of the Mozilla Public License,
# v. 2.0. If a copy of the MPL was not distributed with this file, You can
# obtain one at https://mozilla.org/MPL/2.0/.

.global symbol_table_build, symbol_table_find

.include "boot/definitions.inc"

.equ SYMBOL_PRIME, 1543

.section .rodata

.type symbol_builtin_name_int, @object
symbol_builtin_name_int: .ascii "Int"
.type symbol_builtin_name_word, @object
symbol_builtin_name_word: .ascii "Word"
.type symbol_builtin_name_byte, @object
symbol_builtin_name_byte: .ascii "Byte"
.type symbol_builtin_name_char, @object
symbol_builtin_name_char: .ascii "Char"

# Every type info starts with a word describing what type it is.

# Primitive types have only type size.
.type symbol_builtin_type_int, @object
symbol_builtin_type_int: .word TYPE_PRIMITIVE
	.word 4
.type symbol_builtin_type_word, @object
symbol_builtin_type_word: .word TYPE_PRIMITIVE
	.word 4
.type symbol_builtin_type_byte, @object
symbol_builtin_type_byte: .word TYPE_PRIMITIVE
	.word 1
.type symbol_builtin_type_char, @object
symbol_builtin_type_char: .word TYPE_PRIMITIVE
	.word 1

.section .bss

# The first word of the symbol table is its length.
# Then a list of type infos follows:
#
# record
#   name: String
#   info: ^TypeInfo
# end
.type symbol_table, @object
symbol_table: .zero SYMBOL_PRIME

.section .text

# Searches for a symbol by name.
#
# Parameters:
# a0 - Local symbol table or 0.
# a1 - Length of the symbol to search.
# a2 - Pointer to the symbol name.
#
# Sets a0 to the symbol info.
.type symbol_table_find, @function
symbol_table_find:
	# Prologue.
	addi sp, sp, -32
	sw ra, 28(sp)
	sw s0, 24(sp)
	addi s0, sp, 32

	sw s1, 20(sp) # Current symbol in the table.
	sw s2, 16(sp) # Symbol table length.
	sw s3, 12(sp) # Length of the symbol to search.
	sw s4, 8(sp) # Pointer to the symbol to search.

	mv s3, a1
	mv s4, a2

	la s1, symbol_table
	lw s2, 0(s1)
	addi s1, s1, 4 # Advance to the first symbol in the table.

.Lsymbol_table_find_loop:
	beqz s2, .Lsymbol_table_find_not_found

	# Compare string lengths.
	lw a2, 0(s1)
	bne s3, a2, .Lsymbol_table_find_continue

	# If lengths match, compare the content.
	mv a0, s4
	lw a1, 4(s1)
	call _memcmp

	bnez a0, .Lsymbol_table_find_continue

	lw a0, 8(s1) # Pointer to the symbol.
	j .Lsymbol_table_end

.Lsymbol_table_find_continue:
	addi s2, s2, -1
	j .Lsymbol_table_find_loop

.Lsymbol_table_find_not_found:
	li a0, 0

.Lsymbol_table_end:
	lw s1, 20(sp)
	lw s2, 16(sp)
	lw s3, 12(sp)
	lw s4, 8(sp)

	# Epilogue.
	lw ra, 28(sp)
	lw s0, 24(sp)
	addi sp, sp, 32
	ret

# Build the initial symbols.
#
# Sets a0 to the pointer to the global symbol table.
.type symbol_build, @function
symbol_table_build:
	la a0, symbol_table
	addi t0, a0, 4

	li t1, 3 # Length of the word "Int".
	sw t1, 0(t0)
	la t1, symbol_builtin_name_int
	sw t1, 4(t0)
	la t1, symbol_builtin_type_int
	sw t1, 8(t0)
	lw t1, 0(a0)
	addi t1, t1, 1
	sw t1, 0(a0)
	addi t0, t0, 12

	li t1, 4 # Length of the word "Word".
	sw t1, 0(t0)
	la t1, symbol_builtin_name_word
	sw t1, 4(t0)
	la t1, symbol_builtin_type_word
	sw t1, 8(t0)
	lw t1, 0(a0)
	addi t1, t1, 1
	sw t1, 0(a0)
	addi t0, t0, 12

	li t1, 4 # Length of the word "Byte".
	sw t1, 0(t0)
	la t1, symbol_builtin_name_byte
	sw t1, 4(t0)
	la t1, symbol_builtin_type_byte
	sw t1, 8(t0)
	lw t1, 0(a0)
	addi t1, t1, 1
	sw t1, 0(a0)
	addi t0, t0, 12

	li t1, 4 # Length of the word "Char".
	sw t1, 0(t0)
	la t1, symbol_builtin_name_char
	sw t1, 4(t0)
	la t1, symbol_builtin_type_char
	sw t1, 8(t0)
	lw t1, 0(a0)
	addi t1, t1, 1
	sw t1, 0(a0)
	addi t0, t0, 12

	ret