Handle some edge cases with 0

bmi-calc/main.nasm

@@ -83,6 +83,9 @@ good_height:
     mov rdx,height_notice_post_length
     syscall
 
+    cmp r14,0
+    je print_zero_bmi
+
     ; calculate bmi (kg/(m^2))
     movq xmm1,r14 ; height
     divss xmm1,[_100f] ; cm to m
@@ -110,11 +113,32 @@ good_height:
 
     call clear_stdin
 
-    ; exit
+exit:
     xor rdi,rdi
     mov rax,SYS_exit
     syscall
 
+print_zero_bmi:
+    mov rax,SYS_write
+    mov rdi,FD_stdout
+    mov rsi,bmi_notice_text
+    mov rdx,bmi_notice_length
+    syscall
+
+    mov rax,SYS_write
+    mov rdi,FD_stdout
+    mov rsi,zero_float_text
+    mov rdx,zero_float_length
+    syscall
+
+    mov rax,SYS_write
+    mov rdi,FD_stdout
+    mov rsi,newline_char
+    mov rdx,1
+    syscall
+    
+    jmp exit
+
 clear_stdin:
     ; 16 - read buff
     ; 4 - pollfd.fd
@@ -146,6 +170,10 @@ clear_stdin_end:
     ret
 
 print_float: ; void print_float(float f, int percission)
+    movq rax,xmm0
+    cmp rax,0
+    je print_float_zero
+
     sub rsp,24
     movss xmm1,[_10f]
     mov rcx,rdi
@@ -202,6 +230,13 @@ print_float_reverse_loop:
     add rsp,24
     ret
 
+print_float_zero:
+    mov rax,SYS_write
+    mov rdi,FD_stdout
+    mov rsi,zero_float_text
+    mov rdx,zero_float_length
+    syscall
+    ret
 
 ; on error, return 0 in rax. otherwise, return 1 in rax 
 ; and the result in xmm0
@@ -361,6 +396,8 @@ size_error_text: db "Number too long!",0xA
 size_error_length: equ $ - size_error_text
 period_char: db "."
 newline_char: db 0xA
+zero_float_text: db ".000"
+zero_float_length: equ $ - zero_float_text
 _10f: dd 10.0
 _0.1f: dd 0.1
 _100f: dd 100.0