Smaller vector tables: Add irq_mapped_t.

arch/Kconfig

@@ -636,19 +636,19 @@ config ARCH_MINIMAL_VECTORTABLE
 		provides:
 
 		  #include <nuttx/arch.h>
-		  const irq_t g_irqmap[NR_IRQS] =
+		  const irq_mapped_t g_irqmap[NR_IRQS] =
 		  {
 		    ... IRQ to index mapping values ...
 		  };
 
 		This table is index by the hardware IRQ number and provides a value
-		in the range of 0 to CONFIG_ARCH_NUSER_INTERRUPTS that the new,
+		in the range of 0 to CONFIG_ARCH_NUSER_INTERRUPTS that is the new,
 		mapped index into the vector table.  Unused, unmapped interrupts
-		should be set to (irq_t)-1.  So, for example, if g_irqmap[37] == 24,
+		should be set to (irq_mapped_t)-1.  So, for example, if g_irqmap[37]
-		Then the hardware interrupt vector 37 will be mapped to the interrupt
+		== 24, then the hardware interrupt vector 37 will be mapped to the
-		vector table at index 24.  if g_irqmap[42] == (irq_t)-1, then hardware
+		interrupt vector table at index 24.  if g_irqmap[42] ==
-		interrupt vector 42 is not used and if it occurs will result in an
+		(irq_mapped_t)-1, then hardware interrupt vector 42 is not used and
-		unexpected interrupt crash.
+		if it occurs will result in an unexpected interrupt crash.
 
 config ARCH_NUSER_INTERRUPTS
 	int "Number of interrupts"

include/nuttx/irq.h

@@ -65,7 +65,9 @@
  ****************************************************************************/
 
 #ifndef __ASSEMBLY__
-/* This type is an integer type large enough to hold the largest IRQ number. */
+/* This type is an unsigned integer type large enough to hold the largest
+ * IRQ number.
+ */
 
 #if NR_IRQS <= 256
 typedef uint8_t irq_t;
@@ -75,6 +77,20 @@ typedef uint16_t irq_t;
 typedef uint32_t irq_t;
 #endif
 
+/* This type is an unsigned integer type large enough to hold the largest
+ * mapped vector table index.
+ */
+
+#ifdef CONFIG_ARCH_MINIMAL_VECTORTABLE
+#if CONFIG_ARCH_NUSER_INTERRUPTS <= 256
+typedef uint8_t irq_mapped_t;
+#elif CONFIG_ARCH_NUSER_INTERRUPTS <= 65536
+typedef uint16_t irq_mapped_t;
+#else
+typedef uint32_t irq_mapped_t;
+#endif
+#endif /* CONFIG_ARCH_MINIMAL_VECTORTABLE */
+
 /* This struct defines the form of an interrupt service routine */
 
 typedef int (*xcpt_t)(int irq, FAR void *context, FAR void *arg);
@@ -97,6 +113,20 @@ extern "C"
 #define EXTERN extern
 #endif
 
+#ifdef CONFIG_ARCH_MINIMAL_VECTORTABLE
+/* This is the interrupt vector mapping table.  This must be provided by
+ * architecture specific logic if CONFIG_ARCH_MINIMAL_VECTORTABLE is define
+ * in the configuration.
+ *
+ * REVISIT: Currently declared in sched/irq/irq.h.  This declaration here
+ * introduces a circular dependency since it depends on NR_IRQS which is
+ * defined in arch/irq.h but arch/irq.h includes nuttx/irq.h and we get
+ * here with NR_IRQS undefined.
+ */
+
+/* EXTERN const irq_mapped_t g_irqmap[NR_IRQS]; */
+#endif
+
 /****************************************************************************
  * Public Function Prototypes
  ****************************************************************************/

sched/irq/irq.h

@@ -91,9 +91,16 @@ extern struct irq_info_s g_irqvector[NR_IRQS];
 #endif
 
 #ifdef CONFIG_ARCH_MINIMAL_VECTORTABLE
-/* This is the interrupt vector mapping table */
+/* This is the interrupt vector mapping table.  This must be provided by
+ * architecture specific logic if CONFIG_ARCH_MINIMAL_VECTORTABLE is define
+ * in the configuration.
+ *
+ * REVISIT: This should be declared in include/nuttx/irq.h.  The declaration
+ * at that location, however, introduces a circular include dependency so the
+ * declaration is here for the time being.
+ */
 
-extern const irq_t g_irqmap[NR_IRQS];
+extern const irq_mapped_t g_irqmap[NR_IRQS];
 #endif
 
 #ifdef CONFIG_SMP

sched/irq/irq_dispatch.c

@@ -75,8 +75,8 @@ void irq_dispatch(int irq, FAR void *context)
   else
     {
 #ifdef CONFIG_ARCH_MINIMAL_VECTORTABLE
-      int ndx = g_irqmap[irq];
+      irq_mapped_t ndx = g_irqmap[irq];
-      if ((unsigned)ndx >= CONFIG_ARCH_NUSER_INTERRUPTS)
+      if (ndx >= CONFIG_ARCH_NUSER_INTERRUPTS)
         {
           vector = irq_unexpected_isr;
           arg    = NULL;