game.nasm

; Copyright (C) 2023 Ethan Uppal. All rights reserved.
;
; game.nasm:
; - _game

bits 64

%include "config.nasm"
%include "struct_tui.nasm"

section .text

extern _malloc
extern _free
extern _tui_begin
extern _tui_end
extern _tui_keys
extern _tui_draw

; int game(void);
;   keep r12 = struct tui* tui;
global _game
_game:
    push rbp
    mov rbp, rsp

    ; make tui struct
    mov rdi, SZ_STRUCT_TUI
    call _malloc        ; struct tui* tui = malloc(sizeof(*tui)); // goes in rax
    cmp rax, 0          ; if (!tui)
    jz _game.error      ;     game_error();
    mov r12, rax        ; // <- tui in r12 forever :sunglasses:

    ; begin game (tui in r12)
    mov rdi, r12
    mov esi, W
    mov edx, H
    call _tui_begin     ; tui_begin(tui /* mov rdi, r12 */, W, H);

    ; game loop
.loop:                
    mov rdi, r12                    ; while (true) {
    call _tui_keys                  ;     tui_keys(tui);
    cmp byte [r12 + OFF_tui_c], 'q' ;     if (tui->c == 'q')
    je .end                         ;         goto end;
    jmp _game.loop                  ; }

.end:
    ; end game
    mov rdi, r12
    call _tui_end       ; tui_end(tui /* mov rdi, r12 */);
    mov rdi, r12
    call _free          ; free(tui);

    xor eax, eax
    mov rsp, rbp
    pop rbp
    ret
.error:
    $print error_msg, error_msg_len
    mov eax, 1
    mov rsp, rbp
    pop rbp
    ret

section .rodata
    error_msg: db "A problem occured while running the game :(", 10
    error_msg_len: equ $ - error_msg