C251 Version 3 Operation Timings
X-Tiny Model

The following benchmarks provide a baseline for the execution speed of code generated by the Keil C251 Compiler. Automated test scripts were used to calculate the minimum, average, and maximum time required for each operation.

Each benchmark lists the number of states and the number of seconds required to perform the operation. The state time represents the actual number of instruction cycles. You may specify the oscillator frequency and the clock divisor (for the instruction clock) to obtain execution times in seconds.

Unsigned Character Operations

Operation	Min	Avg	Max
unsigned char +	7 .88 µSecs	7 .88 µSecs	7 .88 µSecs
unsigned char -	7 .88 µSecs	7 .88 µSecs	7 .88 µSecs
unsigned char *	12 1.50 µSecs	12 1.50 µSecs	12 1.50 µSecs
unsigned char /	17 2.13 µSecs	17 2.13 µSecs	17 2.13 µSecs
unsigned char %	17 2.13 µSecs	17 2.13 µSecs	17 2.13 µSecs
unsigned char >>	12 1.50 µSecs	57 7.13 µSecs	110 13.75 µSecs
unsigned char <<	12 1.50 µSecs	51 6.38 µSecs	96 12.00 µSecs

Signed Character Operations

Operation	Min	Avg	Max
signed char +	7 .88 µSecs	7 .88 µSecs	7 .88 µSecs
signed char -	7 .88 µSecs	7 .88 µSecs	7 .88 µSecs
signed char *	12 1.50 µSecs	12 1.50 µSecs	12 1.50 µSecs
signed char /	50 6.25 µSecs	54 6.75 µSecs	60 7.50 µSecs
signed char %	50 6.25 µSecs	54 6.75 µSecs	60 7.50 µSecs
signed char >>	12 1.50 µSecs	51 6.38 µSecs	96 12.00 µSecs
signed char <<	12 1.50 µSecs	51 6.38 µSecs	96 12.00 µSecs
cabs ()	26 3.25 µSecs	30 3.75 µSecs	34 4.25 µSecs

Unsigned Integer Operations

Operation	Min	Avg	Max
unsigned int +	10 1.25 µSecs	10 1.25 µSecs	10 1.25 µSecs
unsigned int -	10 1.25 µSecs	10 1.25 µSecs	10 1.25 µSecs
unsigned int *	21 2.63 µSecs	21 2.63 µSecs	21 2.63 µSecs
unsigned int /	31 3.88 µSecs	31 3.88 µSecs	31 3.88 µSecs
unsigned int %	31 3.88 µSecs	31 3.88 µSecs	31 3.88 µSecs
unsigned int >>	15 1.88 µSecs	60 7.50 µSecs	113 14.13 µSecs
unsigned int <<	15 1.88 µSecs	54 6.75 µSecs	99 12.38 µSecs

Signed Integer Operations

Operation	Min	Avg	Max
signed int +	10 1.25 µSecs	10 1.25 µSecs	10 1.25 µSecs
signed int -	10 1.25 µSecs	10 1.25 µSecs	10 1.25 µSecs
signed int *	21 2.63 µSecs	21 2.63 µSecs	21 2.63 µSecs
signed int /	66 8.25 µSecs	73 9.13 µSecs	80 10.00 µSecs
signed int %	66 8.25 µSecs	73 9.13 µSecs	80 10.00 µSecs
signed int >>	15 1.88 µSecs	54 6.75 µSecs	99 12.38 µSecs
signed int <<	15 1.88 µSecs	60 7.50 µSecs	113 14.13 µSecs
abs ()	28 3.50 µSecs	31 3.88 µSecs	35 4.38 µSecs

Unsigned Long Operations

Operation	Min	Avg	Max
unsigned long +	20 2.50 µSecs	20 2.50 µSecs	20 2.50 µSecs
unsigned long -	20 2.50 µSecs	20 2.50 µSecs	20 2.50 µSecs
unsigned long *	72 9.00 µSecs	72 9.00 µSecs	72 9.00 µSecs
unsigned long /	435 54.38 µSecs	446 55.75 µSecs	461 57.63 µSecs
unsigned long %	435 54.38 µSecs	446 55.75 µSecs	461 57.63 µSecs
unsigned long >>	21 2.63 µSecs	189 23.63 µSecs	387 48.38 µSecs
unsigned long <<	22 2.75 µSecs	154 19.25 µSecs	294 36.75 µSecs

Signed Long Operations

Operation	Min	Avg	Max
signed long +	20 2.50 µSecs	20 2.50 µSecs	20 2.50 µSecs
signed long -	20 2.50 µSecs	20 2.50 µSecs	20 2.50 µSecs
signed long *	72 9.00 µSecs	72 9.00 µSecs	72 9.00 µSecs
signed long /	470 58.75 µSecs	500 62.50 µSecs	533 66.63 µSecs
signed long %	470 58.75 µSecs	500 62.50 µSecs	533 66.63 µSecs
signed long >>	21 2.63 µSecs	185 23.13 µSecs	379 47.38 µSecs
signed long <<	22 2.75 µSecs	154 19.25 µSecs	294 36.75 µSecs
labs ()	37 4.63 µSecs	42 5.25 µSecs	47 5.88 µSecs

Floating-Point Operations

Operation	Min	Avg	Max
float +	166 20.75 µSecs	250 31.25 µSecs	354 44.25 µSecs
float -	136 17.00 µSecs	253 31.63 µSecs	372 46.50 µSecs
float *	143 17.88 µSecs	194 24.25 µSecs	207 25.88 µSecs
float /	683 85.38 µSecs	716 89.50 µSecs	742 92.75 µSecs
modf ()	705 88.13 µSecs	1,206 150.75 µSecs	1,295 161.88 µSecs
fabs ()	35 4.38 µSecs	35 4.38 µSecs	36 4.50 µSecs
ceil ()	964 120.50 µSecs	1,366 170.75 µSecs	1,699 212.38 µSecs
floor ()	964 120.50 µSecs	1,366 170.75 µSecs	1,699 212.38 µSecs
pow ()	666 83.25 µSecs	3,403 425.38 µSecs	9,543 1,192.88 µSecs
sqrt ()	49 6.13 µSecs	951 118.88 µSecs	1,968 246.00 µSecs
exp ()	230 28.75 µSecs	271 33.88 µSecs	4,941 617.63 µSecs
log ()	53 6.63 µSecs	1,850 231.25 µSecs	3,857 482.13 µSecs
log10 ()	235 29.38 µSecs	2,035 254.38 µSecs	4,040 505.00 µSecs
sin ()	555 69.38 µSecs	2,943 367.88 µSecs	3,374 421.75 µSecs
cos ()	522 65.25 µSecs	2,940 367.50 µSecs	3,349 418.63 µSecs
tan ()	3,943 492.88 µSecs	4,050 506.25 µSecs	4,241 530.13 µSecs
asin ()	412 51.50 µSecs	6,499 812.38 µSecs	7,671 958.88 µSecs
acos ()	812 101.50 µSecs	7,041 880.13 µSecs	7,902 987.75 µSecs
atan ()	1,626 203.25 µSecs	3,948 493.50 µSecs	4,631 578.88 µSecs
atan2 ()	1,803 225.38 µSecs	4,627 578.38 µSecs	5,792 724.00 µSecs
sinh ()	2,390 298.75 µSecs	10,129 1,266.13 µSecs	10,765 1,345.63 µSecs
cosh ()	2,456 307.00 µSecs	10,124 1,265.50 µSecs	10,733 1,341.63 µSecs
tanh ()	9,279 1,159.88 µSecs	10,228 1,278.50 µSecs	11,577 1,447.13 µSecs

Buffer Operations

Operation	Min	Avg	Max
memset (10)	139 17.38 µSecs	139 17.38 µSecs	139 17.38 µSecs
memset (100)	1,129 141.13 µSecs	1,129 141.13 µSecs	1,129 141.13 µSecs
memset (1000)	11,029 1,378.63 µSecs	11,029 1,378.63 µSecs	11,029 1,378.63 µSecs
memcpy (10)	192 24.00 µSecs	192 24.00 µSecs	192 24.00 µSecs
memcpy (100)	1,632 204.00 µSecs	1,632 204.00 µSecs	1,632 204.00 µSecs
memcpy (1000)	16,032 2,004.00 µSecs	16,032 2,004.00 µSecs	16,032 2,004.00 µSecs
memmove (10 with overlap)	207 25.88 µSecs	207 25.88 µSecs	207 25.88 µSecs
memmove (100 with overlap)	1,647 205.88 µSecs	1,647 205.88 µSecs	1,647 205.88 µSecs
memmove (1000 with overlap)	16,047 2,005.88 µSecs	16,047 2,005.88 µSecs	16,047 2,005.88 µSecs

Memory Allocation Operations

Operation	Min	Avg	Max
malloc (), 99.7% successful	56 7.00 µSecs	250 31.25 µSecs	642 80.25 µSecs
free ()	72 9.00 µSecs	219 27.38 µSecs	455 56.88 µSecs

Notes Note

These tests were performed and measured using the µVision Debugger. Test code was compiled with the C251 Version 3.60 C Compiler using the X-Tiny Memory Model, 251-source mode, ROM(LARGE), and Optimization Level 7-SPEED.

C251 Version 3 Operation TimingsX-Tiny Model