On Mon, 11 May 2009, Øyvind Harboe wrote:
> On Mon, May 11, 2009 at 5:25 PM, Nicolas Pitre <[email protected]> wrote:
> > On Mon, 11 May 2009, Øyvind Harboe wrote:
> >
> >> 2009/5/11 Nicolas Pitre <[email protected]>:
> >> >
> >> > cc1: warnings being treated as errors
> >> > jtag.c: In function ‘jtag_check_value_mask_callback':
> >> > jtag.c:703: error: cast from pointer to integer of different size
> >> > jtag.c: In function ‘jtag_add_scan_check':
> >> > jtag.c:740: error: cast to pointer from integer of different size
> >>
> >> Is this a 64 bit host?
> >
> > Yes.
>
> Hmm.... so what's the correct way to cast a void * to an int (keeping only
> as many bits as will fit in an int) on a 64 bit system?
You cast to a long first, like:
diff --git a/src/jtag/jtag.c b/src/jtag/jtag.c
index 0be66c2..b59d02d 100644
--- a/src/jtag/jtag.c
+++ b/src/jtag/jtag.c
@@ -700,7 +700,7 @@ int jtag_check_value_inner(u8 *captured, u8
*in_check_value, u8 *in_check_mask,
static int jtag_check_value_mask_callback(u8 *in, jtag_callback_data_t data1,
jtag_callback_data_t data2, jtag_callback_data_t data3)
{
- return jtag_check_value_inner(in, (u8 *)data1, (u8 *)data2, (int)data3);
+ return jtag_check_value_inner(in, (u8 *)data1, (u8 *)data2,
(int)(long)data3);
}
static void jtag_add_scan_check(void (*jtag_add_scan)(int num_fields,
scan_field_t *fields, tap_state_t state),
@@ -737,7 +737,7 @@ static void jtag_add_scan_check(void (*jtag_add_scan)(int
num_fields, scan_field
if ((fields[i].check_value!=NULL)&&(fields[i].in_value!=NULL))
{
/* this is synchronous for a minidriver */
- jtag_add_callback4(jtag_check_value_mask_callback,
fields[i].in_value, fields[i].check_value, fields[i].check_mask,
(jtag_callback_data_t)fields[i].num_bits);
+ jtag_add_callback4(jtag_check_value_mask_callback,
fields[i].in_value, fields[i].check_value, fields[i].check_mask,
(jtag_callback_data_t)(long)fields[i].num_bits);
}
if (fields[i].allocated)
{
This however starts to become really ugly and deserves some comment as
to why such trickery is used. Even the original code might benefit from
some explanation for those casts.
> Alternatively I could use a less clever scheme and have a union of int
> & void *...
I'd say clearer and cleaner rather than less clever. Generated code
would be the same, except on big endian 64-bit machines where you'd end
up keeping the top pointer bits instead. In that case you'd need an
union definition where a dummy int would need to be inserted as padding.
Probably the cleanest solution would be to encapsulate the two casts
within a macro, and put a nice comment above the macro definition to
explain why this is done. Similar to:
/*
* We don't care about the real pointer but only the low 32 bits of it
* for some funky hash lookup. The double cast removes warnings on
* 64-bit machines.
*/
#define PTR_TO_HASH(X) ((int)(long)(x))
Nicolas
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