made hello world build on Apple

section_1/hello_world/.vscode/settings.json

@@ -0,0 +1,6 @@
+{
+    "cSpell.ignoreWords": [
+        "onditionally",
+        "onsole"
+    ]
+}

section_1/hello_world/README.md

@@ -10,6 +10,11 @@ the C into ARM V8 assembly language.
 At every step, we'll completely explain the code and document what has
 changed from version to version so that little background is assumed.
 
+[Special Bonus](#special-bonus---build-on-linux-and-apple-silicon) can
+be found by following the link. The code found there uses the macro
+suite developed by the author that allows code to be written once and
+built on both the Mac M family as well as on Linux.
+
 ## V1 in C++
 
 Here is the code to a program that prints to the console, the contents
@@ -670,18 +675,62 @@ job.
 We do maintain that understanding assembly language principles will
 improve your higher level language coding.
 
+## Special Bonus - Build on Linux AND Apple Silicon
+
+[Here](./v6.S) is the source code shown below.
+
+[Here](./apple-linux-convergence.S) is the source code to the macro
+suite that allows you to write the code once and build on both the Apple
+M family and upon Linux.
+
+The documentation can be found [here](./../../macros/).
+
+```text
+#include "apple-linux-convergence.S"                        // 1 
+                                                            // 2 
+        .text                                               // 3 
+        .p2align    2                                       // 4 
+        GLABEL      main                                    // 5 
+                                                            // 6 
+MAIN                                                        // 7 
+        PUSH_P      x21, x30                                // 8 
+        PUSH_R      x29                                     // 9 
+        mov         x29, sp                                 // 10 
+                                                            // 11 
+        mov         x21, x1                                 // 12 
+                                                            // 13 
+1:      ldr         x0, [x21], 8                            // 14 
+        cbz         x0, 2f                                  // 15 
+        CRT         puts                                    // 16 
+        b           1b                                      // 17 
+                                                            // 18 
+2:      POP_R       x29                                     // 19 
+        POP_P       x21, x30                                // 20 
+        mov         x0, xzr                                 // 21 
+        ret                                                 // 22 
+                                                            // 23 
+        .end                                                // 24 
+```
+
+The push and pop macros simply save typing but the other macros sense
+if you are building on Linux or on Apple M family. In this case, the
+macros are helping with underscores but the macro suite contains more
+sophisticated helpers as well.
+
 ## Questions
 
 ### 1
 
-(T | F) It is the compiler's job to reduce a higher level language to assembly language.
+(T | F) It is the compiler's job to reduce a higher level language to
+assembly language.
 
-Answer: True - The "compiler" is just one step in the "compilation" process. In fact it
+Answer: True - The "compiler" is just one step in the "compilation"
-is step 2. Invoking the "preprocessor" is step 1.
+process. In fact it is step 2. Invoking the "preprocessor" is step 1.
 
 ### 2
 
-(T | F) Failing to mark `main` as a `global` will result in a syntax error.
+(T | F) Failing to mark `main` as a `global` will result in a syntax
+error.
 
 Answer: False - a linker error will happen, not a syntax error.
 
@@ -689,8 +738,9 @@ Answer: False - a linker error will happen, not a syntax error.
 
 \___ and ___ implement the braces in C and C++.
 
-Answer: labels and branches - the closing brace of a `while` loop for example,
+Answer: labels and branches - the closing brace of a `while` loop for
-is a branch instruction. The opening brace of a `while` is a label.
+example, is a branch instruction. The opening brace of a `while` is a
+label.
 
 ### 4
 
@@ -701,12 +751,14 @@ if a_register has value 0
     then goto label
 ```
 
-Answer: True - `cbz` stands for "compare and branch if zero". There is also
+Answer: True - `cbz` stands for "compare and branch if zero". There is
-a `cbnz` instruction. To test for other Boolean conditions, use `cmp`.
+also a `cbnz` instruction. To test for other Boolean conditions, use
+`cmp`.
 
 ### 5
 
-While this chapter is entitled "Hello World," the example used isn't actually "Hello World." Here is a "Hello World" for you to complete:
+While this chapter is entitled "Hello World," the example used isn't
+actually "Hello World." Here is a "Hello World" for you to complete:
 
 ```text
    .global main                                                       

section_1/hello_world/apple-linux-convergence.S

@@ -0,0 +1,116 @@
+/*  Macros to permit the "same" assembly language to build on ARM64
+    Linux systems as well as Apple Silicon systems.
+
+    See the fuller documentation at:
+    https://github.com/pkivolowitz/asm_book/blob/main/macros/README.md
+
+    Perry Kivolowitz
+    A Gentle Introduction to Assembly Language
+*/
+
+.macro  GLD_PTR     xreg, label
+#if defined(__APPLE__)
+        adrp	    \xreg, _\label@GOTPAGE
+        ldr	        \xreg, [\xreg, _\label@GOTPAGEOFF]
+#else
+        ldr         \xreg, =\label
+        ldr         \xreg, [\xreg]
+#endif
+.endm
+
+.macro  GLD_ADDR    xreg, label     // Get a global address
+#if defined(__APPLE__)
+        adrp	    \xreg, _\label@GOTPAGE
+        add         \xreg, \xreg, _\label@GOTPAGEOFF
+#else
+        ldr         \xreg, =\label
+#endif
+.endm
+
+.macro  LLD_ADDR xreg, label
+#if defined(__APPLE__)
+        adrp    \xreg, \label@PAGE
+        add     \xreg, \xreg, \label@PAGEOFF
+#else
+        ldr         \xreg, =\label
+#endif
+.endm
+
+.macro  LLD_DBL xreg, dreg, label
+#if defined(__APPLE__)
+        adrp    \xreg, \label@PAGE
+        add     \xreg, \xreg, \label@PAGEOFF
+        ldur    \dreg, [\xreg]
+//      fmov    \dreg, \xreg
+#else
+        ldr     \xreg, =\label
+        ldur    \dreg, [\xreg]
+#endif
+.endm
+
+.macro  LLD_FLT xreg, sreg, label
+#if defined(__APPLE__)
+        adrp    \xreg, \label@PAGE
+        add     \xreg, \xreg, \label@PAGEOFF
+        ldur    \sreg, [\xreg]
+#else
+        ldr     \xreg, =\label
+        ldur    \sreg, [\xreg]
+#endif
+.endm
+
+.macro GLABEL label
+#if defined(__APPLE__)
+        .global _\label
+#else
+        .global \label
+#endif
+.endm
+
+.macro MAIN
+#if defined(__APPLE__)
+_main:
+#else
+main:
+#endif
+.endm
+
+.macro  CRT label
+#if defined(__APPLE__)
+        bl  _\label
+#else
+        bl  \label
+#endif
+.endm
+
+.macro  START_PROC          // after starting label
+        .cfi_startproc
+.endm
+
+.macro  END_PROC            // after the return
+        .cfi_endproc
+.endm
+
+.macro  PUSH_P  a, b 
+        stp     \a, \b, [sp, -16]!
+.endm
+
+.macro  PUSH_R  a 
+        str     \a, [sp, -16]!
+.endm
+
+.macro  POP_P   a, b 
+        ldp     \a, \b, [sp], 16
+.endm
+
+.macro  POP_R   a 
+        ldr     \a, [sp], 16
+.endm
+
+.macro  MIN     src_a, src_b, dest
+        csel    \dest, \src_a, \src_b, GT
+.endm
+
+.macro  MAX     src_a, src_b, dest
+        csel    \dest, \src_a, \src_b, LT
+.endm

section_1/hello_world/v6.S

@@ -0,0 +1,24 @@
+#include "apple-linux-convergence.S"
+
+        .text
+        .p2align    2
+        GLABEL      main
+
+MAIN
+        PUSH_P      x21, x30
+        PUSH_R      x29
+        mov         x29, sp
+
+        mov         x21, x1
+
+1:      ldr         x0, [x21], 8
+        cbz         x0, 2f
+        CRT         puts
+        b           1b
+
+2:      POP_R       x29
+        POP_P       x21, x30
+        mov         x0, xzr
+        ret
+
+        .end