Merge branch 'master' of https://git.eleves.ens.fr/mpepin/sysdig

test/asm/faster_clock.s

+.text
+#TODO: replace $s6 and $s7 to load $ra directly + compute offset
+
+main:
+# initialisation of the month discrimination
+# 0..0101011010101
+  addi $s0, $zero, 2773
+# TODO: change initialisation to input value (for example, linux time stamp)
+# initialisation of the value keeping the minutes and seconds
+# Format : DDDD.UUUU.dddd.uuuu where d/D = digit, u/U = unit  for sec/min
+  xor $s1, $s1, $s1
+
+# initialisation of the value keeping the hours and the days
+# Format : ddddd.HHHH.hhhh where d = day, h/H = hour (unit/digit)
+  addi $s2, $zero, 4352
+
+# initialisation of the value keeping the years
+  addi $s3, $zero, 2017
+  xor $s3, $s3, $s3
+
+# initialisation of the value counting the leap years and the month
+# Format : mmmm.ccccc where m = month, c = counter
+  addi $s4, $zero, 32
+
+# initialisation of the value keeping track of the current time
+  xor $s5, $s5, $s5
+
+# $s6 and $s7 will be used to store addresses for future jumps
+# $t7 will be used as a flag for when we are processing hours
+  j clock
+
+clock:
+# We loop until a second has passed.
+# Comment this part for performance tests.
+#  li $v0, 5
+#  syscall
+#  beq $v0, $s5, clock
+# We update the time.
+#  add $s5, $zero, $v0
+# We empty the buffer
+  la $a0, end
+  li $v0, 4
+  syscall
+# We now start the calculations for the next second.
+  j seconds
+
+# This is for when we are updating an hour of the form 2Xh
+print_hour:
+  addi $t5, $zero, 4
+  bne $a1, $t5, print_num
+  addi $a2, $zero, -1
+
+print_zero:
+  addi $a0, $zero, 16
+  xor $a1, $a1, $a1
+  li $v0, 4
+  syscall
+
+# We use this block to compute the display of a digit - seconds, minutes, hours
+digits:
+# We set the return value
+  add $ra, $zero, $s6 #FIXME_ra
+# We test whether we reached 24 hours
+# Remember that $t2 = 2 when we deal with hours.
+  bne $t2, $zero, print_zero_digit
+  addi $a2, $a2, 1
+  addi $t5, $zero, 6
+  beq $t5, $a2, print_zero_digit
+
+print_num_d:
+# We multiply $a2 by 8 to get the address of the correct string
+  sll $t5, $a2, 3
+  addi $a0, $t5, 16
+  li $v0, 4
+  syscall
+  jr $ra
+
+print_zero_digit:
+  addi $a0, $zero, 16
+  addi $t0, $zero, 1
+  xor $a2, $a2, $a2
+  li $v0, 4
+  jr $ra
+
+
+# We use this block to compute the display of a unit - seconds, minutes or hours
+unit:
+# We increment $a1
+  addi $a1, $a1, 1
+# We use $t0 as an easy way to access 0, but here $t0 = $zero
+# We set the return adress to be the digit
+  add $ra, $zero, $s7 #FIXME_ra
+# We load the string according to the value of $a1
+# 16 is the adress of the first string
+  addi $t5, $zero, 10
+  beq $a1, $t5, print_zero
+  and $t2, $t7, $a2
+  bne $t2, $zero, print_hour
+
+print_num:
+# We multiply $a1 by 8 to get the address of the right string
+  sll $t5, $a1, 3 #FIXME sll doesn't work
+  addi $a0, $t5, 16
+  li $v0, 4
+  syscall
+  jr $ra
+
+
+
+# The following blocks compute a possible update of the month.
+# This is where we compute whether it is a leap year or not.
+day_29:
+# We are sent here from the tests on the day
+# $a1 is the day, $a2 is the month
+  addi $t4, $zero, 2
+  bne $a2, $t4, update_days
+# We test whether the year is a leap year
+# First, if the modulo is 4
+  andi $t4, $s3, 3
+  beq $t4, $zero, year_100
+  addi $t0, $zero, 1
+  j update_days
+
+# Then, if it is a multiple of four, whether our leap year counter is 25
+year_100:
+# Update the counter first.
+  addi $s4, $s4, 1
+  addi $t4, $zero, 25
+  beq $s4, $t4, year_400
+
+# If we didn't jump, it's a leap year.
+leap_year:
+# The day should be 1
+  addi $a1, $zero, 1
+  addi $t0, $zero, 1
+  j update_days
+
+year_400:
+# We need to reset our counter
+  xor $s4, $s4, $s4
+# We test whether the year is a multiple of 400
+# If it is, it's a leap year
+  andi $t4, $a1, 15
+  beq $t4, $zero, leap_year
+  addi $a1, $a1, 1
+  j update_days
+
+# This is to test whether we are a 29/02
+day_30:
+  addi $t4, $zero, 2
+  bne $a2, $t4, update_days
+# If this is indeed a 29/02
+  addi $a1, $zero, 1
+  addi $t0, $zero, 1
+  j update_days
+
+day_31:
+# We use the discrimination from $s0 to decide if a month has 30 or 31 days
+  srlv $t4, $s0, $a2
+  andi $t4, $t4, 1
+# $t4 = 0 if the month has 30 days, $t4 = 1 otherwise
+  bne $t4, $zero, update_days
+# j day_32
+
+# Here, we always need to update the month.
+day_32:
+  addi $a1, $zero, 1
+  addi $t0, $zero, 1
+  j update_days
+
+# For when we need to roll around to a new year
+month_13:
+  addi $a2, $zero, 1
+  addi $t0, $zero, 1
+  j update_months
+
+
+# Beginning of each loop
+seconds:
+  xor $t7, $t7, $t7
+  xor $a1, $a1, $a1
+  xor $a2, $a2, $a2
+# We fetch the stored values of the seconds
+  andi $a1, $s1, 15
+  andi $a2, $s1, 240
+  srl $a2, $a2, 4
+# We empty the print argument
+  xor $a0, $a0, $a0
+  xor $t0, $t0, $t0
+# $t2 is the flag for when we reached 24h.
+  xor $t2, $t2, $t2
+  la $s7, update_sec_units
+  la $s6, update_sec_digits
+  j unit
+
+update_sec_digits:
+# Update the digits
+  andi $s1, $s1, 65295
+  sll $a2, $a2, 4
+  or $s1, $a2, $s1
+
+update_sec_units:
+# Update the units
+  andi $s1, $s1, 65520
+  or $s1, $a1, $s1
+  beq $t0, $zero, clock
+#  j minutes
+
+minutes:
+  xor $a0, $a0, $a0
+  xor $a1, $a1, $a1
+  xor $a2, $a2, $a2
+  xor $t0, $t0, $t0
+# We fetch the stored values of the minutes
+  andi $a1, $s1, 3840
+  srl $a1, $a1, 8
+  andi $a2, $s1, 61440
+  srl $a2, $a2, 12
+  la $s7, update_min_units
+  la $s6, update_min_digits
+  j unit
+
+update_min_digits:
+# Update the digits
+  andi $s1, $s1, 4095
+  sll $a2, $a2, 12
+  or $s1, $a2, $s1
+
+update_min_units:
+# Update the units
+  andi $s1, $s1, 61695
+  sll $a1, $a1, 8
+  or $s1, $a1, $s1
+  beq $t0, $zero, clock
+#  j hours
+
+hours:
+  xor $a0, $a0, $a0
+  xor $a1, $a1, $a1
+  xor $a2, $a2, $a2
+  xor $t0, $t0, $t0
+# We are treating the hours, so $t7 = 2
+  addi $t7, $zero, 2
+# We fetch the stored values of the hours
+  andi $a1, $s2, 15
+  andi $a2, $s2, 240
+  srl $a2, $a2, 4
+# We set the return adresses
+  la $s7, update_hours_units
+  la $s6, update_hours_digits
+  j unit
+
+update_hours_digits:
+# Update the digits
+  andi $s2, $s2, 65295
+  sll $a2, $a2, 4
+  or $s2, $a2, $s2
+
+update_hours_units:
+# Update the units
+  andi $s2, $s2, 65520
+  or $s2, $a1, $s2
+  beq $t0, $zero, clock
+#  j days
+
+days:
+  xor $a0, $a0, $a0
+  xor $a1, $a1, $a1
+  xor $a2, $a2, $a2
+  xor $t0, $t0, $t0
+# We fetch the current day and month
+  andi $a1, $s2, 7936
+  srl $a1, $a1, 8
+  andi $a2, $s4, 480
+  srl $a2, $a2, 5
+# We update the day
+  addi $a1, $a1, 1
+# We have some tests to do according to the next day
+  addi $t3, $zero, 29
+  beq $a1, $t3, day_29
+  addi $t3, $t3, 1
+  beq $a1, $t3, day_30
+  addi $t3, $t3, 1
+  beq $a1, $t3, day_31
+  addi $t3, $t3, 1
+  beq $a1, $t3, day_32
+# If we haven't jumped, we must stay in the same month
+
+update_days:
+# We print the new day
+  add $a0, $zero, $a1
+  li $v0, 1
+  syscall
+  la $a0, line
+  li $v0, 4
+  syscall
+# Screen $s2 to erase the days
+  andi $s2, $s2, 255
+  sll $a1, $a1, 8
+  or $s2, $a1, $s2
+  beq $t0, $zero, clock
+# j months
+
+months:
+  xor $t0, $t0, $t0
+# At this point, $a2 already contains the month
+  addi $a2, $a2, 1
+  addi $t4, $zero, 13
+  beq $a2, $t4, month_13
+# j update_months
+
+update_months:
+# We print the new month
+  add $a0, $zero, $a2
+  li $v0, 1
+  syscall
+  la $a0, line
+  li $v0, 4
+  syscall
+# Screen $s3 to erase the month
+  andi $s4, $s4, 31
+  sll $a2, $a2, 5
+  or $s4, $s4, $a2
+  beq $t0, $zero, clock
+# j years
+
+years:
+# We only have to add 1 to the current year.
+  addi $s3, $s3, 1
+# We print the new year
+  add $a0, $zero, $s3
+  li $v0, 1
+  syscall
+  la $a0, line
+  li $v0, 4
+  syscall
+# Time to restart the loop
+  j clock
+
+.data
+  zero: .asciiz "1011111\n"
+  one: .asciiz "0000110\n"
+  two: .asciiz "0111011\n"
+  three: .asciiz "0101111\n"
+  four: .asciiz "1100110\n"
+  five: .asciiz "1101101\n"
+  six: .asciiz "1111101\n"
+  seven: .asciiz "0000111\n"
+  eight: .asciiz "1111111\n"
+  nine: .asciiz "1101111\n"
+  line: .asciiz "\n"
+  end: .asciiz "EOF\n"