Reduce outputted instructions for printf call

The entire printf was a macro so all the code would be inlined.
Now the macro is only a wrapper. And it will jump to the one
implementation.

This makes the final binary size smaller and the stepping with gdb more
straightforward.

src/bss/buffers.asm

@@ -9,3 +9,5 @@ printf_arg_6_buf resb 8
 printf_arg_7_buf resb 8
 printf_arg_8_buf resb 8
 
+printf_num_args resb 4
+

src/printf.asm

@@ -1,5 +1,8 @@
 %define MAX_PRINTF_ARGS 8
 
+; TODO: do not segfault when we write out of those bounds
+%define MAX_PRINTF_LEN 2048
+
 %macro printlnf 1-*
     printf %{1:-1}
     call print_newline
@@ -16,41 +19,51 @@
     %xdefine num_args %count(%{1:-1})
     %assign num_args (num_args-1)
 
+    ; rax = is null terminated format str
+    str_to_stack %1
+
     %if num_args == 0
-        _printf_args %1, 0
+        mov dword [printf_num_args], 0
+        call _printf_args
     %elif num_args == 1
         mov qword [printf_arg_1_buf], %{2:2}
-        _printf_args %1, 1
+        mov dword [printf_num_args], 1
+        call _printf_args
     %elif num_args == 2
         mov qword [printf_arg_1_buf], %{2:2}
         mov qword [printf_arg_2_buf], %{3:3}
-        _printf_args %1, 2
+        mov dword [printf_num_args], 2
+        call _printf_args
     %elif num_args == 3
         mov qword [printf_arg_1_buf], %{2:2}
         mov qword [printf_arg_2_buf], %{3:3}
         mov qword [printf_arg_3_buf], %{4:4}
-        _printf_args %1, 3
+        mov dword [printf_num_args], 3
+        call _printf_args
     %elif num_args == 4
         mov qword [printf_arg_1_buf], %{2:2}
         mov qword [printf_arg_2_buf], %{3:3}
         mov qword [printf_arg_3_buf], %{4:4}
         mov qword [printf_arg_4_buf], %{5:5}
-        _printf_args %1, 4
+        mov dword [printf_num_args], 4
+        call _printf_args
     %elif num_args == 5
         mov qword [printf_arg_1_buf], %{2:2}
         mov qword [printf_arg_2_buf], %{3:3}
         mov qword [printf_arg_3_buf], %{4:4}
         mov qword [printf_arg_4_buf], %{5:5}
         mov qword [printf_arg_5_buf], %{6:6}
-        _printf_args %1, 5
+        mov dword [printf_num_args], 5
+        call _printf_args
     %elif num_args == 6
         mov qword [printf_arg_1_buf], %{2:2}
         mov qword [printf_arg_2_buf], %{3:3}
         mov qword [printf_arg_3_buf], %{4:4}
         mov qword [printf_arg_4_buf], %{5:5}
         mov qword [printf_arg_5_buf], %{6:6}
         mov qword [printf_arg_6_buf], %{7:7}
-        _printf_args %1, 6
+        mov dword [printf_num_args], 6
+        call _printf_args
     %elif num_args == 7
         mov qword [printf_arg_1_buf], %{2:2}
         mov qword [printf_arg_2_buf], %{3:3}
@@ -59,7 +72,8 @@
         mov qword [printf_arg_5_buf], %{6:6}
         mov qword [printf_arg_6_buf], %{7:7}
         mov qword [printf_arg_7_buf], %{8:8}
-        _printf_args %1, 7
+        mov dword [printf_num_args], 7
+        call _printf_args
     %elif num_args == 8
         mov qword [printf_arg_1_buf], %{2:2}
         mov qword [printf_arg_2_buf], %{3:3}
@@ -69,7 +83,8 @@
         mov qword [printf_arg_6_buf], %{7:7}
         mov qword [printf_arg_7_buf], %{8:8}
         mov qword [printf_arg_8_buf], %{9:9}
-        _printf_args %1, 8
+        mov dword [printf_num_args], 8
+        call _printf_args
     %else
         jmp %%error_many_args
     %endif
@@ -88,6 +103,10 @@
     exit 1
 
     %%okay_many_args:
+
+    ; frees stack string
+    mov rsp, rbp
+
     pop_registers
 %endmacro
 
@@ -116,36 +135,36 @@ _printf_fill_arg:
     pop rax
     ret
 
-%macro _printf_args 2
+_printf_args:
     ; _printf_args [format str] [num args]
+    ;  rax = format string
     ;  needs the labels
+    ;
+    ;  [printf_num_args]
+    ;
     ;  [printf_arg_1_buf]
     ;  [printf_arg_2_buf]
     ;  ...
     ;
     ;  to be filled. The amount depends on num_args.
     push_registers
 
-    ; TODO: do not segfault when we write out of those bounds
-    %define MAX_PRINTF_LEN 2048
-
-    ; rax = is null terminated format str
-    str_to_stack %1
 
     ; r8 is the arg index
     ; we increment before compare
     ; so 1 = is the first
     ; but it will be %2 because %1 is the fmt string
     mov r8, 0
 
+    mov rbp, rsp
     sub rsp, MAX_PRINTF_LEN
     ; r10 is index in final output string
     mov r10, 0
     ; r11 is pointer to start of output string
     lea r11, [rbp-MAX_PRINTF_LEN]
 
     mov rcx, 0
-%%printf_fmt_char_loop:
+.__printf_fmt_char_loop:
     mov r9b, byte [rax+rcx]
     inc rcx
 
@@ -155,69 +174,69 @@ _printf_fill_arg:
     inc r10
 
     cmp r9b, '%'
-    je %%printf_fmt_char_loop_got_percentage
+    je .__printf_fmt_char_loop_got_percentage
     cmp r9b, '\'
-    je %%printf_fmt_char_loop_got_backslash
+    je .__printf_fmt_char_loop_got_backslash
 
-    jmp %%printf_fmt_char_loop_check_repeat
+    jmp .__printf_fmt_char_loop_check_repeat
 
-%%printf_fmt_char_loop_got_backslash:
+.__printf_fmt_char_loop_got_backslash:
     ; \n newline
     mov r9b, byte [rax+rcx]
     cmp r9b, 'n'
     dec r10
     mov byte [r11+r10], 0xa
     inc r10
     inc rcx
-    jmp %%printf_fmt_char_loop_check_repeat
+    jmp .__printf_fmt_char_loop_check_repeat
 
-%%printf_fmt_char_loop_got_percentage:
+.__printf_fmt_char_loop_got_percentage:
     mov r9b, byte [rax+rcx]
     cmp r9b, 'd'
-    je %%printf_fmt_char_loop_got_fmt_d
+    je .__printf_fmt_char_loop_got_fmt_d
     cmp r9b, 'p'
-    je %%printf_fmt_char_loop_got_fmt_p
+    je .__printf_fmt_char_loop_got_fmt_p
 
     puts "error: printf got invalid format character"
     exit 1
 
-%%printf_fmt_char_loop_got_fmt_d:
+.__printf_fmt_char_loop_got_fmt_d:
     mov rsi, int32_to_str
     call _printf_fill_arg
-    jmp %%printf_fmt_char_loop_check_repeat
+    jmp .__printf_fmt_char_loop_check_repeat
 
-%%printf_fmt_char_loop_got_fmt_p:
+.__printf_fmt_char_loop_got_fmt_p:
     mov rsi, ptr_to_str
     call _printf_fill_arg
-    jmp %%printf_fmt_char_loop_check_repeat
+    jmp .__printf_fmt_char_loop_check_repeat
 
-%%printf_fmt_char_loop_check_repeat:
+.__printf_fmt_char_loop_check_repeat:
 
     cmp r9b, 0
-    jne %%printf_fmt_char_loop
+    jne .__printf_fmt_char_loop
 
     ; print output buffer
     dec r10
     printn r11, r10
 
-    ; frees stack string
-    ; and copy buffer
+    ; free copy buffer
     mov rsp, rbp
 
-    cmp r8, %2
-    je %%printf_args_end
+    cmp r8d, [printf_num_args]
+    je .__printf_args_end
 
     puts "error: printf number of args does not match number of args in format string"
     print "      expected args: "
-    mov rax, %2
+    mov rax, 0
+    mov eax, [printf_num_args]
     call println_int32
     print "           got args: "
     mov rax, r8
     call println_int32
     exit 1
 
-    %%printf_args_end:
+.__printf_args_end:
 
     pop_registers
-%endmacro
+    ret
 

src/teeworlds_asmr.asm

@@ -120,8 +120,8 @@ section .bss
 section .text
 
 %include "src/macros.asm"
-%include "src/printf.asm"
 %include "src/syscalls.asm"
+%include "src/printf.asm"
 %include "src/logger.asm"
 %include "src/hex.asm"
 %include "src/terminal.asm"

tests/assert.asm

@@ -43,8 +43,8 @@ section .bss
 section .text
 
 %include "src/macros.asm"
-%include "src/printf.asm"
 %include "src/syscalls.asm"
+%include "src/printf.asm"
 %include "src/logger.asm"
 %include "src/hex.asm"
 %include "src/udp.asm"