September Morn Update

Task/Call-a-foreign-language-function/ARM-Assembly/call-a-foreign-language-function.arm

@@ -0,0 +1,52 @@
+/* ARM assembly Raspberry PI  */
+/*  program forfunction.s   */
+
+/* Constantes    */
+.equ STDOUT, 1     @ Linux output console
+.equ EXIT,   1     @ Linux syscall
+.equ WRITE,  4     @ Linux syscall
+/* Initialized data */
+.data
+szString: .asciz "Hello word\n"
+
+/* UnInitialized data */
+.bss
+
+/*  code section */
+.text
+.global main
+main:                            @ entry of program
+    push {fp,lr}                 @ saves registers
+
+    ldr r0,iAdrszString          @ string address
+    bl strdup                    @ call function C
+                                 @ return new pointer
+    bl affichageMess             @ display dup string
+    bl free                      @ free heap
+
+100:                             @ standard end of the program */
+    mov r0, #0                   @ return code
+    pop {fp,lr}                  @restaur 2 registers
+    mov r7, #EXIT                @ request to exit program
+    swi 0                        @ perform the system call
+iAdrszString:      .int szString
+
+/******************************************************************/
+/*     display text with size calculation                         */
+/******************************************************************/
+/* r0 contains the address of the message */
+affichageMess:
+    push {r0,r1,r2,r7,lr}                          @ save  registres
+    mov r2,#0                                      @ counter length
+1:                                                 @ loop length calculation
+    ldrb r1,[r0,r2]                                @ read octet start position + index
+    cmp r1,#0                                      @ if 0 its over
+    addne r2,r2,#1                                 @ else add 1 in the length
+    bne 1b                                         @ and loop
+                                                   @ so here r2 contains the length of the message
+    mov r1,r0                                      @ address message in r1
+    mov r0,#STDOUT                                 @ code to write to the standard output Linux
+    mov r7, #WRITE                                 @ code call system "write"
+    svc #0                                         @ call systeme
+    pop {r0,r1,r2,r7,lr}                           @ restaur des  2 registres */
+    bx lr                                          @ return

Task/Call-a-foreign-language-function/Crystal/call-a-foreign-language-function.crystal

@@ -0,0 +1,12 @@
+@[Link("c")] # name of library that is passed to linker. Not needed as libc is linked by stdlib.
+lib LibC
+  fun free(ptr : Void*) : Void
+  fun strdup(ptr : Char*) : Char*
+end
+
+s1 = "Hello World!"
+p = LibC.strdup(s1) # returns Char* allocated by LibC
+s2 = String.new(p)
+LibC.free p # pointer can be freed as String.new(Char*) makes a copy of data
+
+puts s2