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Re-write the Telechips I2C delay routine in assembler to stop the compiler optimising it away. Tested with EABI and non-EABI compilers.

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@26872 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Rob Purchase 2010-06-16 21:03:57 +00:00
parent ff8e76e9e5
commit 6c94ce590d
1 changed files with 4 additions and 3 deletions
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7
firmware/target/arm/i2c-telechips.c
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@ -27,9 +27,10 @@
/* Delay loop based on CPU frequency (FREQ>>22 is 7..45 for 32MHz..192MHz) */ /* Delay loop based on CPU frequency (FREQ>>22 is 7..45 for 32MHz..192MHz) */
static inline void delay_loop(void) static inline void delay_loop(void)
{ {
unsigned long x; asm volatile (" mov %[freq], %[freq], asr#22 \n\t"
for (x = (unsigned)(FREQ>>22); x; x--) "1: subs %[freq], %[freq], #1 \n\t"
asm volatile("nop"); " bne 1b"
: : [freq] "r" (cpu_frequency) : "memory");
} }
#define DELAY delay_loop() #define DELAY delay_loop()