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parse_si_suffix() {
if [[ $1 =~ ([0-9]+)(([A-Z]+)?) ]]; then
local value=${BASH_REMATCH[1]}
local unit=${BASH_REMATCH[2]}
local mult=""
if [[ $unit == "" ]]; then
echo $value
return 0
fi
case $unit in
B) mult=1 ;;
K) mult=1024 ;;
M) mult=$((1024*1024)) ;;
G) mult=$((1024*1024*1024)) ;;
T) mult=$((1024*1024*1024*1024)) ;;
P) mult=$((1024*1024*1024*1024*1024)) ;;
E) mult=$((1024*1024*1024*1024*1024*1024)) ;;
*) return 1 ;;
esac
echo $((mult*value))
else
return 1
fi
}
# random <min> <max> -- echoes random number >= min and <= max.
# Examples:
# random 0 1
# random 1K 1G
# random 1 1K
random() {
local min=$(parse_si_suffix $1)
local max=$(parse_si_suffix $2)
shuf -n 1 --input-range=$min-$max
}
# unique_file [<suffix>] -- generates an unique string
# files created by this function are automatically removed at the end of a test
unique_file() {
local suffix=""
if (( $# >= 1 )); then
suffix="_$1"
fi
echo "temp_$(date +%s.%N)_$$$suffix"
}
# pseudorandom_init [<seed>] -- sets a seed (default or specified) for pseudorandom generator
pseudorandom_init() {
pseudorandom_seed_file_="$TEMP_DIR/$(unique_file pseudorandom_seed)"
if (( $# >= 1 )); then
local seed=$1
else
local seed=115249 # some prime number
fi
echo $seed > "$pseudorandom_seed_file_"
}
# pseudo random number generator with glibc algorithm (drawing bits 0..30)
prng() {
if [[ ! -e "$pseudorandom_seed_file_" ]]; then
return 1
fi
local seed=$(cat "$pseudorandom_seed_file_")
seed=$(( (1103515245 * seed + 12345) % 2147483648 ))
echo $seed | tee "$pseudorandom_seed_file_"
}
# pseudorandom <min> <max> -- echoes random number >= min and <= max up to 2^62
# Examples:
# pseudorandom 0 1
# pseudorandom 1K 1G
# pseudorandom 1 1K
pseudorandom() {
local min=$(parse_si_suffix $1)
local max=$(parse_si_suffix $2)
local shift=2147483648 # 2^31
local pass1=$(prng)
local pass2=$(( $shift * $(prng) ))
local result=$(( min + (pass1 + pass2) % (max - min + 1) ))
echo $result
}
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