Differences

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--- vbcc [2024/08/20 19:46] – [The linker script] Add missing __DD variable pulkomandy
+++ vbcc [2024/08/27 17:20] (current) – [The configuration file] Fix typos, add missing asv pulkomandy
@@ Line 50: / Line 50: @@
     * lib/
       * startup.o
+      * libvc.a
+    * include/
+      * ctype.h
+      * stdlib.h
+      * string.h
     * vlink.cmd
+The content of each file or how to generate them is detailed below.
 ===== The configuration file =====
@@ Line 60: / Line 66: @@
 -ccv=vbccunsp -I"$VBCC"/targets/unsp-vsmile/include %s -o= %s %s -O=%ld
 -as=vasmunsp_std -quiet -ile -Fvobj %s -o %s
+-asv=vasmunsp_std -ile -Fvobj %s -o %s
 -rm=rm %s
 -rmv=rm %s
--ld=vlink -ole -b rawbin1 -Cvbcc -T"$VBCC"/targets/unsp-vsmile/vlink.cmd -L"$VBCC"/targets/unsp-vmsile/lib "$VBCC"/targets/unsp-vsmile/lib/startup.o %s %s -o %s -lvc
+-ld=vlink -ole -b rawbin1 -Cvbcc -T"$VBCC"/targets/unsp-vsmile/vlink.cmd -L"$VBCC"/targets/unsp-vsmile/lib "$VBCC"/targets/unsp-vsmile/lib/startup.o %s %s -o %s -lvc
--ldv=vlink -ole -b rawbin1 -Cvbcc -T"$VBCC"/targets/unsp-vsmile/vlink.cmd -L"$VBCC"/targets/unsp-vmsile/lib "$VBCC"/targets/unsp-vsmile/lib/startup.o %s %s -o %s -lvc -Mmapfile
+-ldv=vlink -ole -b rawbin1 -Cvbcc -T"$VBCC"/targets/unsp-vsmile/vlink.cmd -L"$VBCC"/targets/unsp-vsmile/lib "$VBCC"/targets/unsp-vsmile/lib/startup.o %s %s -o %s -lvc -Mmapfile
--l2=vlink -ole -b rawbin1 -Cvbcc -T"$VBCC"/targets/unsp-vsmile/vlink.cmd -L"$VBCC"/targets/unsp-vmsile/lib %s %s -o %s
+-l2=vlink -ole -b rawbin1 -Cvbcc -T"$VBCC"/targets/unsp-vsmile/vlink.cmd -L"$VBCC"/targets/unsp-vsmile/lib %s %s -o %s
--l2v=vlink -ole -b rawbin1 -Cvbcc -T"$VBCC"/targets/unsp-vsmile/vlink.cmd -L"$VBCC"/targets/unsp-vmsile/lib %s %s -o %s -Mmapfile
+-l2v=vlink -ole -b rawbin1 -Cvbcc -T"$VBCC"/targets/unsp-vsmile/vlink.cmd -L"$VBCC"/targets/unsp-vsmile/lib %s %s -o %s -Mmapfile
 </code>
@@ Line 186: / Line 193: @@
         ; Copy the initialized variables into RAM
         ; __DL = length of variables section
-        ; __DS = start of variables section in ROM
+        ; __DS = start of variables section in RAM
-        LD R1, 0x0000
+        ; __DD = start of variables section in ROM
-        LD R2, __DS
+        LD R1, __DS
+        LD R2, __DD
         LD R3, __DL
         JZ gomain
@@ Line 202: / Line 210: @@
 gomain:
         GOTO main
+; Handlers for indirect calls. Used by VBCC to handle function pointers, because unSP does not have
+; an indirect call (CALL R1 or similar) operation and it is not trivial to emulate one.
+.globl __indirect_R1
+.globl __indirect_R2
+.globl __indirect_R3
+.globl __indirect_R4
+__indirect_R1:
+        LD PC,R1
+__indirect_R2:
+        LD PC,R2
+__indirect_R3:
+        LD PC,R3
+__indirect_R4:
+        LD PC,R4
 ; The interrupt vectors section, contains pointers to the interrupt handlers
@@ Line 240: / Line 263: @@
 Note: the -ile option tells vasm that files included using the incbin directive are in little endian. This gives the same results as the official unSP toolchain when importing binary files.
+===== The C library =====
+vbcc does not come with an open source C library. A full one from other sources could be compiled, but we don't need a complete C library.
+So here is a very minimal one with enough support to run the compiler and to run Contiki, which has minimal needs from the C library (just a few string functions).
+<code c>
+/*
+ * Copyright (C) 2024 Adrien Destugues <pulkomandy@pulkomandy.tk>
+ *
+ * Distributed under terms of the MIT license.
+ */
+int strlen(const char* str)
+{
+        int i = 0;
+        while(*str++) i++;
+        return i;
+}
+int isprint(char c)
+{
+        return c >= 32;
+}
+void strcpy(const char* src, char* dst)
+{
+        char c;
+        while (c = *src++)
+                *dst++ = c;
+        *dst = 0;
+}
+void memset(int* s, int v, int n)
+{
+        while(--n >= 0)
+                *s++ = v;
+}
+int strncmp(const char* a, const char* b, int n)
+{
+        while(--n >= 0) {
+                if (*a != *b)
+                        return *a - *b;
+                if (*a == 0)
+                        return *b;
+                if (*b == 0)
+                        return -*a;
+        }
+}
+int __div(int a, int b)
+{
+        int c = 0;
+        while (a >= b) {
+                a -= b;
+                c++;
+        }
+        return c;
+}
+int __mod(int a, int b)
+{
+        while (a >= b) {
+                a -= b;
+        }
+        return a;
+}
+</code>
+To generate the libc.a file:
+<code sh>
+vc +vsmile -nostdlib -O3 -c libc.c
+ar cru libvc.a libc.o
+</code>
+We also need some include files. ctype.h and stdlib.h can be empty, but they are used by Contiki so they must exist.
+string.h has some basic functions declarations and type definitions:
+<code c>
+#ifndef __STRING_H
+#define __STRING_H 1
+/*
+  Adapt according to stddef.h.
+*/
+#ifndef __SIZE_T
+#define __SIZE_T 1
+typedef unsigned int size_t;
+#endif
+#undef NULL
+#define NULL ((void *)0)
+/*
+  Many of these functions should perhaps be implemented as
+  inline-assembly or assembly-functions.
+  Most suitable are:
+  - memcpy
+  - strcpy
+  - strlen
+  - strcmp
+  - strcat
+*/
+void *memcpy(void *,const void *,size_t n);
+void *memmove(void *,const void *,size_t);
+void *memset(void *,int,size_t);
+int memcmp(const void *,const void *,size_t);
+void *memchr(const void *,int,size_t);
+char *strcat(char *,const char *);
+char *strncat(char *,const char *,size_t);
+char *strchr(const char *,int);
+size_t strcspn(const char *,const char *);
+char *strpbrk(const char *,const char *);
+char *strrchr(const char *,int);
+size_t strspn(const char *,const char *);
+char *strstr(const char *,const char *);
+char *strtok(char *,const char *);
+char *strerror(int);
+size_t strlen(const char *);
+char *strcpy(char *,const char *);
+char *strncpy(char *,const char *,size_t);
+int strcmp(const char *,const char *);
+int strncmp(const char *,const char *,size_t);
+int strcoll(const char *,const char *);
+size_t strxfrm(char *,const char *,size_t);
+#endif
+</code>
 ====== Running the compiler ======
+Note: make sure you have set the VBCC environment variable as explained earlier, otherwise the compiler will not find the target configuration and will complain and not compile anything.
 To compile a .c file into a .o file: