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| author | Rafaël Carré <rafael.carre@gmail.com> | 2010-06-18 19:14:08 +0000 |
|---|---|---|
| committer | Rafaël Carré <rafael.carre@gmail.com> | 2010-06-18 19:14:08 +0000 |
| commit | 7a9033179f34ba5175b5dc13c674d21235f2f98a (patch) | |
| tree | 0c76fc01b163dae4b4fa9fbf9a828b539a10ea00 /firmware/target/arm/as3525/system-as3525.c | |
| parent | 955bb4004fcfbc762db7c9364665a40fa2018e7e (diff) | |
as3525*: make udelay() be a simple busy loop
it achieves all the requirements, work fine on c200v2, and is much simpler
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@26933 a1c6a512-1295-4272-9138-f99709370657
Diffstat (limited to 'firmware/target/arm/as3525/system-as3525.c')
| -rw-r--r-- | firmware/target/arm/as3525/system-as3525.c | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/firmware/target/arm/as3525/system-as3525.c b/firmware/target/arm/as3525/system-as3525.c index 940f183c63..aa98aff852 100644 --- a/firmware/target/arm/as3525/system-as3525.c +++ b/firmware/target/arm/as3525/system-as3525.c @@ -326,6 +326,26 @@ int system_memory_guard(int newmode) return 0; } +void udelay(unsigned short usecs) +{ + unsigned cycles_per_usec; + unsigned delay; + + if (cpu_frequency == CPUFREQ_MAX) { + cycles_per_usec = (CPUFREQ_MAX + 999999) / 1000000; + } else { + cycles_per_usec = (CPUFREQ_NORMAL + 999999) / 1000000; + } + + delay = (usecs * cycles_per_usec + 3) / 4; + + asm volatile( + "1: subs %0, %0, #1 \n" /* 1 cycle */ + " bne 1b \n" /* 3 cycles */ + : : "r"(delay) + ); +} + #ifndef BOOTLOADER #ifdef HAVE_ADJUSTABLE_CPU_FREQ |