updated some samples

.vscode/sftp.json

@@ -0,0 +1,12 @@
+{
+    "name": "My Server",
+    "host": "localhost",
+    "protocol": "sftp",
+    "port": 2222,
+    "username": "user",
+    "remotePath": "./asm_book",
+    "uploadOnSave": true,
+    "useTempFile": false,
+    "openSsh": true,
+    "password": "a"
+}

section_1/regs/align.s

@@ -1,15 +1,37 @@
-        .global	main
-        .text
-        .align	2
+#include "apple-linux-convergence.S"
 
-main:	mov     x0, xzr
-        ldr     x1, =ram
-        strb    w0, [x1]
-        strh    w0, [x1]
-        str     w0, [x1]
-        str     x0, [x1]
+/*  The purpose of this program is to use gdb or lldb to watch a
+    region of memory get overwritten first with a byte, then a short,
+    then an int and finally with a long.
+
+    As can be seen, the program produces no output of its own. Rather,
+    use of a debugger is needed.
+
+    The gdb command to examine the memory located at "ram" is:
+    x/xg $x1
+*/
+
+        GLABEL	    main
+        .text
+        .p2align    2
+
+
+MAIN
+        START_PROC
+        PUSH_P      x29, x30
+        mov         x29, sp
+
+    	mov         x0, xzr
+        ldr         x1, =ram
+        strb        w0, [x1]
+        strh        w0, [x1]
+        str         w0, [x1]
+        str         x0, [x1]
+
+        POP_P       x29, x30
         ret
-    
+        END_PROC
+
         .data
 ram:    .quad   0xFFFFFFFFFFFFFFFF
 

section_1/regs/apple-linux-convergence.S

@@ -0,0 +1,151 @@
+/*  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
+
+/*  Fetching the address of the externally defined errno is quite
+    different on Apple and Linux. This macro leaves the address of
+    errno in x0.
+*/
+.macro  ERRNO_ADDR
+#if defined(__APPLE__)
+        bl      ___error
+#else
+        bl      __errno_location
+#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
+
+/*  The smaller of src_a and src_b is put into dest. A cmp instruction
+    or other instruction that sets the flags must be performed first.
+    This macro makes it easy to remember which register does what in the
+    csel.
+    
+    Thank you to u/TNorthover for nudge to add the cmp.
+*/
+
+.macro  MIN     src_a, src_b, dest
+        cmp     \src_a, \src_b
+        csel    \dest, \src_a, \src_b, LT
+.endm
+
+/*  The larger of src_a and src_b is put into dest. A cmp instruction
+    or other instruction that sets the flags must be performed first.
+    This macro makes it easy to remember which register does what in the
+    csel.
+
+    Thank you to u/TNorthover for nudge to add the cmp.
+*/
+
+.macro  MAX     src_a, src_b, dest
+        cmp     \src_a, \src_b
+        csel    \dest, \src_a, \src_b, GT
+.endm
+
+.macro  AASCIZ      label, string
+        .p2align    2
+\label: .asciz      "\string"
+.endm

section_1/regs/badstack.s

@@ -1,3 +1,6 @@
+/*  The purpose of this program is to crash due to not manipulating the
+    stack in multiples of 16.
+*/
         .global main
         .text
         .align  2

section_1/regs/quinn.S

@@ -22,6 +22,6 @@ main:		stp		x29, x30, [sp, -16]!
 
 		.data
 
-fmt:		.asciz		"Number: %d\n"
+fmt:	.asciz		"Number: %d\n"
 		.end