diff options
Diffstat (limited to 'c/src/lib/libbsp/sh/gensh1/include/bsp.h')
| -rw-r--r-- | c/src/lib/libbsp/sh/gensh1/include/bsp.h | 33 |
1 files changed, 32 insertions, 1 deletions
diff --git a/c/src/lib/libbsp/sh/gensh1/include/bsp.h b/c/src/lib/libbsp/sh/gensh1/include/bsp.h index 8f676d07fe..8422599b42 100644 --- a/c/src/lib/libbsp/sh/gensh1/include/bsp.h +++ b/c/src/lib/libbsp/sh/gensh1/include/bsp.h @@ -68,8 +68,39 @@ extern "C" { #define Lower_tm27_intr() /* Constants */ +#ifndef MHZ +#error Missing MHZ +#endif + +/* + * Simple spin delay in microsecond units for device drivers. + * This is very dependent on the clock speed of the target. + * + * Since we don't have a real time clock, this is a very rough + * approximation, assuming that each cycle of the delay loop takes + * approx. 4 machine cycles. + * + * e.g.: MHZ = 20 => 5e-8 secs per instruction + * => 4 * 5e-8 secs per delay loop + */ + +#define delay( microseconds ) \ +{ register unsigned int _delay = (microseconds) * (MHZ / 4 ); \ + asm volatile ( \ +"0: add #-1,%0\n \ + nop\n \ + cmp/pl %0\n \ + bt 0b\ + nop" \ + :: "r" (_delay) ); \ +} -#define MHZ 20 +/* + * For backward compatibility only. + * Do not rely on them being present in future + */ +#define CPU_delay( microseconds ) delay( microseconds ) +#define sh_deley( microseconds ) delay( microseconds ) /* * Defined in the linker script 'linkcmds' |