.gitignore

@@ -2,4 +2,3 @@
 *.pdb
 *.obj
 *sublime-workspace
-*.exe

README.md

@@ -1,8 +0,0 @@
-This repo is me working through the book The Art of 64 Bit Assembly. 
-To build listings in the `src/` folder simply call the `build.bat`
-script with the listing number:
-
-```batch
-build 1_8 //  don't add .asm extension
-
-```

src/1_3.asm

@@ -1,13 +0,0 @@
-    .CODE
-
-    option casemap:none     ; make all symbols case sensitive (like C)
-
-    public asm_func         ; make this visible outside of this source
-
-asm_func PROC ; start procedure
-    
-    ret
-
-asm_func ENDP ; end procedure
-        
-    END

src/1_4.asm

@@ -1,15 +0,0 @@
-; a user defined proc
-
-    .code 
-
-asm_proc proc
-    ret             ; return from the procedure
-asm_proc endp
-
-main proc           ; the main procedure
-    call asm_proc   ; call our proc
-    ret
-main endp
-    end
-
-

src/1_5.asm

@@ -1,21 +0,0 @@
-    option casemap:none
-
-    .data
-
-fmt_str byte 'Hello World!', 10, 0 ; here 10 is the newline feed
-
-    .code
-
-    externdef printf:proc
-
-    public asm_func
-
-asm_func proc
-    sub rsp, 56
-    lea rcx, fmt_str ; load the format string into the RCX register to be used by the printf
-    call printf
-    add rsp, 56
-    ret
-asm_func endp
-    
-    end

src/1_8.asm

@@ -1,59 +1,59 @@
+; assembly that shows how to return values to a
+; a C function
+
     option casemap:none
 
 ; constants
-nl      =   10  ; newline
+nl      =       10
-maxlen  =   256 ; max len of the string
+maxlen  =       256
 
     .data
 
-title_string    byte    'Listing 1_8', 0
+title_str   byte        "Listing 1-8", 0
-prompt_string   byte    'Enter a string: ', 0
+prompt      byte        "Enter a string: ", 0
-format_string   byte    'User entered: "%s" ', nl, 0
+fmt_string  byte        "User entered: '%s'", nl, 0
+
+; make `maxlen` copies/duplicates of size byte, each uinitialized
+input       byte maxlen dup (?)
 
-input   byte    maxlen dup (?) ; make maxlen copies of byte, each uninitialized
 
     .code
 
     externdef printf:proc
     externdef readline:proc
 
-
-;; get_title procedure -------------------------
-;; get_title moves the address of the byte containing the string "Listing 1_8", 0
-;; into the RAX register, it does this usig the LEA instruction
     public get_title
+
+; procedure loads the address of the title_str into the RAX
+; register, this is the register where C expects to find 
+; the return of this proc. (WINDOWS ABI)
 get_title proc
     
-    lea rax, title_string   ; load address of title_string into rax
+    lea rax, title_str  ; load address of title string in RAX register
     ret
 
 get_title endp
 
+; ASM Main function
     public asm_main
 asm_main proc 
 
-    sub rsp, 56
+    sub     rsp, 56
     
-    ;; first we want to print a prompt, to do this we use the stdio function printf, 
+    lea     rcx, prompt     ; load prompt string address into RCX register
-    ;; we need to make the arguments for printf avaialble by loading the address of the
+    call    printf          ; this is the reigster where ABI tells us to place arguments
-    ;; byte prompt_string into RCX
-    lea rcx, prompt_string
-    call printf
 
-    mov input, 0 ;; clear the input
+    mov     input, 0        ; ensure the input string is terminated with 0
 
-    ; read user input by calling readline from out cpp program. We load the required 
+    lea     rcx, input      ; load input address to rcx register
-    ; arguments into the registers RCX, and RDX and then call readline
+    mov     rdx, maxlen     ; move maxlen into rdx register
-    lea rcx, input
+    call    readline        ; use rcx and rdx as arguments to call readline
-    mov rdx, maxlen
-    call readline
 
-    ; load RCX and RDX with arugments to printf, to print back to the user
+    lea     rcx, fmt_string
-    lea rcx, format_string
+    lea     rdx, input
-    lea rdx, input
+    call    printf
-    call printf
 
-    add rsp, 56
+    add     rsp, 56
     ret
 
 asm_main endp

src/build.bat

@@ -1,9 +1,4 @@
 @echo off
 echo ~~~~ starting build ~~~~
-
-REM /nolog is dont show MS info at run
-REM /c is compile dont link
-REM /Zi is debug info
-REM /Cp is preserve cases
 ml64 /nologo /c /Zi /Cp %1.asm
 cl /nologo /O2 /Zi /utf-8 /EHa /Fe%1.exe c.cpp %1.obj

src/c.cpp

@@ -8,7 +8,7 @@ extern "C"
 {
     void asm_main(void);
 
-    // function is defined in the asm file
+
     char *get_title(void);
 
     int readline(char* dest, int maxlen);

src/listing_1_9.cpp

@@ -1 +0,0 @@
-listing_1_9.cpp

src/main.cpp

@@ -2,15 +2,12 @@
 
 extern "C" 
 {
-    // Function written in ASM
     void asm_func(void);
-}
+};
 
-int main() 
+int main(void) 
 {
-    printf("calling asm function\n");
+    printf("calling asm main\n");
     asm_func();
-    printf("returned from asm function\n");
+    printf("return from asm main\n");
-
-    return(0);
 }