small improvements

* Update TOTO list
* Change the type of gint_vbr to comply with a new warning in GCC 9
* Add strcmp()

TODO

@@ -13,13 +13,12 @@ Complementary elements on existing code.
 * topti:     support unicode fonts
 * gray:      find good values for more models than the Graph 35+E II
 * render:    get rid of GINT_NEED_VRAM and #define vram gint_vram if you need
-* dma:       dma_memcpy() and dma_memset(), possibly requiring alignment
 * dma:       maybe relax the 4-byte size constraint for dma_memset()
-* core:      try to leave add-in without reset in case of fatal exception
+* core:      try to leave add-in without reset in case of panic
 * topti:     support Unicode fonts
 * hardware:  fill in the HWMEM_FITTLB flag
 * keyboard:  think of extended functions
-* keyboard:  add an intermediate-level API with some sort of IsKeyDown()
+* keyboard:  implement keydown() in an event-compliant way
 * cpg:       spread spectrum on fxcg50
 * bopti:     blending modes for monochrome bitmaps (use topti assembler)
 * display:   use more of topti's assembler in drect()

include/gint/std/string.h

@@ -19,7 +19,10 @@ size_t strlen(char const *str);
 /* strncpy(): Copy a string with a size limit */
 char *strncpy(char *dst, char const *src, size_t n);
 
-/* strcat(): Concatenation of src in dest*/
+/* strcat(): Concatenation a string to a pre-allocated space */
 char *strcat(char *dest, const char *src);
 
+/* strcmp(): Compare NUL-terminated strings */
+int strcmp(char const *s1, char const *s2);
+
 #endif /* GINT_STD_STRING */

src/core/setup.c

@@ -10,7 +10,7 @@
 #include <gint/mpu/intc.h>
 
 /* VBR address, from the linker script */
-extern char gint_vbr;
+extern char gint_vbr[];
 /* System's VBR address */
 GBSS static uint32_t system_vbr;
 /* Size of exception and TLB handler */

src/std/string.c

@@ -6,24 +6,30 @@
 #include <gint/defs/attributes.h>
 #include <stdarg.h>
 
-GWEAK size_t strlen(const char *str)
+GWEAK size_t strlen(char const *str)
 {
 	int len = 0;
 	while(str[len]) len++;
 	return len;
 }
 
-GWEAK char *strncpy(char *dst, const char *src, size_t n)
+GWEAK char *strncpy(char *dst, char const *src, size_t n)
 {
 	size_t i = 0;
 	while(i < n && (dst[i] = src[i])) i++;
 	return dst;
 }
 
-GWEAK char *strcat(char *dest, const char *src)
+GWEAK char *strcat(char *dest, char const *src)
 {
 	unsigned long fin_dest = strlen(dest);
 	unsigned int i;
 	for (i = 0 ; i <= strlen(src) ; i++) dest[fin_dest + i] = src[i];
 	return dest;
 }
+
+GWEAK int strcmp(char const *s1, char const *s2)
+{
+	while(*s1 && *s1 == *s2) s1++, s2++;
+	return *s1 - *s2;
+}