asm2: improve example

asm2/example_c_asm_and_coproc/compile.sh

@@ -1 +1 @@
-nasm sum.asm -f elf && gcc main.c sum.o -m32
+nasm utils.asm -f elf && gcc main.c utils.o -m32

asm2/example_c_asm_and_coproc/main.c

@@ -5,14 +5,14 @@ Copyright 2020 KoroLion (github.com/KoroLion)
 #include <stdio.h>
 
 float sum(float a, float b);
+float fx(float x);
 
 int main() {
-    float a, b;
-    scanf("%f %f", &a, &b);
-
-    float c = sum(a, b);
-
+    float c = sum(1.5, 2.1);
     printf("%f\n", c);
 
+    float y = fx(2);
+    printf("%f\n", y);
+
     return 0;
 }

asm2/example_c_asm_and_coproc/sum.asm

@@ -1,19 +0,0 @@
-; Copyright 2020 KoroLion (github.com/KoroLion)
-
-global sum
-
-section .data
-section .bss
-    temp: resb 4
-
-section .text
-
-; sum(x, y)
-sum:
-    finit
-    fld dword [esp + 4]  ; = x
-    fadd dword [esp + 8] ; += y
-    fst dword [temp] ; [temp] = st0
-
-    mov eax, [temp]
-    ret

asm2/example_c_asm_and_coproc/utils.asm

@@ -0,0 +1,36 @@
+; Copyright 2020 KoroLion (github.com/KoroLion)
+
+global sum
+global fx
+
+section .data
+section .bss
+    temp: resb 4
+
+section .text
+
+; float sum(float x, float y)
+; return x + y
+sum:
+    finit
+
+    fld dword [esp + 4]  ; st0 = x
+    fadd dword [esp + 8] ; st0 += y
+
+    ret ; returns st0 to c
+
+; float fx(float x)
+; return 1 / (x + 2)
+fx:
+    ; st1
+    fld dword [esp + 4] ; st1 = x
+    mov dword [temp], 2
+    fiadd dword [temp] ; st1 += 2
+
+    ; st0
+    mov dword [temp], 1
+    fild dword [temp] ; st0 = 1
+
+    fdiv st0, st1 ; st0 /= st1
+
+    ret ; returns st0 to c