From 352c98e502893dee405d0bd8301264fca3b79179 Mon Sep 17 00:00:00 2001 From: Laurent Vivier Date: Tue, 25 Aug 2015 17:09:36 +0200 Subject: [PATCH] arm: clarify the use of muldiv64() muldiv64() is used to convert microseconds into CPU ticks. But it is not clear and not commented. This patch uses macro to clearly identify what is used: time, CPU frequency and ticks. For an elapsed time and a given frequency, we compute how many ticks we have. Signed-off-by: Laurent Vivier Reviewed-by: Peter Crosthwaite Acked-by: Peter Maydell --- target-arm/helper.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) diff --git a/target-arm/helper.c b/target-arm/helper.c index 12ea88fd52..83679970b4 100644 --- a/target-arm/helper.c +++ b/target-arm/helper.c @@ -12,6 +12,8 @@ #include /* For crc32 */ #include "exec/semihost.h" +#define ARM_CPU_FREQ 1000000000 /* FIXME: 1 GHz, should be configurable */ + #ifndef CONFIG_USER_ONLY static inline bool get_phys_addr(CPUARMState *env, target_ulong address, int access_type, ARMMMUIdx mmu_idx, @@ -706,8 +708,8 @@ void pmccntr_sync(CPUARMState *env) { uint64_t temp_ticks; - temp_ticks = muldiv64(qemu_clock_get_us(QEMU_CLOCK_VIRTUAL), - get_ticks_per_sec(), 1000000); + temp_ticks = muldiv64(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL), + ARM_CPU_FREQ, NANOSECONDS_PER_SECOND); if (env->cp15.c9_pmcr & PMCRD) { /* Increment once every 64 processor clock cycles */ @@ -745,8 +747,8 @@ static uint64_t pmccntr_read(CPUARMState *env, const ARMCPRegInfo *ri) return env->cp15.c15_ccnt; } - total_ticks = muldiv64(qemu_clock_get_us(QEMU_CLOCK_VIRTUAL), - get_ticks_per_sec(), 1000000); + total_ticks = muldiv64(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL), + ARM_CPU_FREQ, NANOSECONDS_PER_SECOND); if (env->cp15.c9_pmcr & PMCRD) { /* Increment once every 64 processor clock cycles */ @@ -766,8 +768,8 @@ static void pmccntr_write(CPUARMState *env, const ARMCPRegInfo *ri, return; } - total_ticks = muldiv64(qemu_clock_get_us(QEMU_CLOCK_VIRTUAL), - get_ticks_per_sec(), 1000000); + total_ticks = muldiv64(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL), + ARM_CPU_FREQ, NANOSECONDS_PER_SECOND); if (env->cp15.c9_pmcr & PMCRD) { /* Increment once every 64 processor clock cycles */ -- 2.11.4.GIT