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| etienne@etienne-ThinkPad-W520: ~/Documents lsb_release -a
| | ==Operating systems basic terms and introduction== |
| No LSB modules are available.
| | ===Tasks of the kernel, operating system, RAM, processor etc=== |
| Distributor ID: Ubuntu
| | Applications use the kernel to connect to computer system resources (CPU; memory and devices). It manages input/output requests from software, translating them into data processing instructions for the central processing unit. It is also responsible for managing memory, and for managing and communicating with computing peripherals, like printers, speakers, etc. It is crucial part of the operating system. |
| Description: Ubuntu 14.04.3 LTS
| |
| Release: 14.04
| |
| Codename: trusty
| |
|
| |
|
| | Tasks: |
| | *CPU time planning |
| | **Real time vs Package processing |
| | **Syncing |
| | **Multitasking with multiple CPUs |
| | *Memory management |
| | **MMU - memory management unit |
| | **Cache and swap |
| | *I/O management |
| | **Syncronous |
| | **Asyncronous |
| | *File management |
| | **Permissions |
| | **File system hierarchy |
|
| |
|
| etienne@etienne-ThinkPad-W520: ~/Documents uname -sr
| |
| Linux 3.19.0-25-generic
| |
|
| |
|
| etienne@etienne-ThinkPad-W520: ~/Documents cat /proc/cpuinfo
| | An operating system (OS) is system software that manages computer hardware and software resources and provides common services for computer programs (API). |
| processor : 0
| | Tasks: |
| vendor_id : GenuineIntel
| | *Hardware management |
| cpu family : 6
| | **CPU time |
| model : 42
| | **Memory management |
| model name : Intel(R) Core(TM) i7-2860QM CPU @ 2.50GHz
| | **Input/output management |
| stepping : 7
| | **Network management |
| microcode : 0x23
| | *Computer system management |
| cpu MHz : 800.781
| | **Application management |
| cache size : 8192 KB
| | **Input/output device management |
| physical id : 0
| | **User authentication and authorization |
| siblings : 8
| | **Data management between devices |
| core id : 0
| |
| cpu cores : 4
| |
| apicid : 0
| |
| initial apicid : 0
| |
| fpu : yes
| |
| fpu_exception : yes
| |
| cpuid level : 13
| |
| wp : yes
| |
| bugs :
| |
| bogomips : 4983.75
| |
| clflush size : 64
| |
| cache_alignment : 64
| |
| address sizes : 36 bits physical, 48 bits virtual
| |
| power management:
| |
|
| |
|
| processor : 1
| | ==User management== |
| vendor_id : GenuineIntel
| | ===What is authorization and authentication?=== |
| cpu family : 6
| | ===What is password salt and what is it used for?=== |
| model : 42
| | ==Working with files and permissions== |
| model name : Intel(R) Core(TM) i7-2860QM CPU @ 2.50GHz
| | ===Explain the way why permissions are needed and how they are set for users=== |
| stepping : 7
| | ===Explain special permissions=== |
| microcode : 0x23
| | ==User environment== |
| cpu MHz : 849.316
| | ===What are user environment variables used for? Name two reasons=== |
| cache size : 8192 KB
| | ==Processes== |
| physical id : 0
| | ===How to stream data between processes=== |
| siblings : 8
| | ===What are different type of processes (running, stopped, killed, zombie etc)=== |
| core id : 0
| | ===Different examples of how to benefit from sending signals between processes=== |
| cpu cores : 4
| | ==Software management== |
| apicid : 1
| | ===Name various ways how to manage software in LInux=== |
| initial apicid : 1
| | ===What are the pros and cons of Linux software management=== |
| fpu : yes
| | ===What are software repositories?=== |
| fpu_exception : yes
| | ===What are libraries?=== |
| cpuid level : 13
| | ==Filesystem hierarchy== |
| wp : yes
| | ===Explain the hierarchy according to FHS=== |
| bugs :
| | ===Name specific folder meanings and usage=== |
| bogomips : 4983.75
| | ==Documentation== |
| clflush size: 64
| | ===Best practices of a good documentation=== |
| cache_alignment : 64
| | ===Why should we document?=== |
| address sizes : 36 bits physical, 48 bits virtual
| | ==Security== |
| power management:
| | ===List the different type of security breaches=== |
| | | ===What should the user/admin do to prevent the attack?=== |
| processor : 2
| | ==Partitioning and swap area== |
| vendor_id : GenuineIntel
| | ===What are the primary, extended and logical partitions? What limitations are set with these partitions types?=== |
| cpu family : 6
| | ===When isn’t it a good idea to use swap area?=== |
| model : 42
| | ==RAID and LVM technologies== |
| model name : Intel(R) Core(TM) i7-2860QM CPU @ 2.50GHz
| | ===Name main uses and features of both technologies=== |
| stepping : 7
| | ==SAN, NAS and CAS technologies== |
| microcode : 0x23
| | ===Name main uses and features of all the technologies=== |
| cpu MHz : 801.074
| | ==Backup and recovery== |
| cache size : 8192 KB
| | ===Backup and recovery plans=== |
| physical id : 0
| | ==Monitoring and log files== |
| siblings : 8
| | ===Active and passive monitoring=== |
| core id : 1
| | ===Types of alerts=== |
| cpu cores : 4
| | ===Benefits of monitoring=== |
| apicid : 2
| | ===Centralized logs=== |
| initial apicid : 2
| | ==Ethical, social and personal aspects of working in IT field== |
| fpu : yes
| | ===Impostor syndrome, teamwork, burnout=== |
| fpu_exception : yes
| |
| cpuid level : 13
| |
| wp : yes
| |
| bugs :
| |
| bogomips : 4983.75
| |
| clflush size : 64
| |
| cache_alignment : 64
| |
| address sizes : 36 bits physical, 48 bits virtual
| |
| power management:
| |
| | |
| processor : 3
| |
| vendor_id : GenuineIntel
| |
| cpu family : 6
| |
| model : 42
| |
| model name : Intel(R) Core(TM) i7-2860QM CPU @ 2.50GHz
| |
| stepping : 7
| |
| microcode : 0x23
| |
| cpu MHz : 800.097
| |
| cache size : 8192 KB
| |
| physical id : 0
| |
| siblings : 8
| |
| core id : 1
| |
| cpu cores : 4
| |
| apicid : 3
| |
| initial apicid : 3
| |
| fpu : yes
| |
| fpu_exception : yes
| |
| cpuid level : 13
| |
| wp : yes
| |
| bugs :
| |
| bogomips : 4983.75
| |
| clflush size: 64
| |
| cache_alignment : 64
| |
| address sizes : 36 bits physical, 48 bits virtual
| |
| power management:
| |
| | |
| etienne@etienne-ThinkPad-W520: ~/Documents arch
| |
| x86_64
| |
| | |
| etienne@etienne-ThinkPad-W520: ~/Documents cat /proc/meminfo
| |
| MemTotal: 8128036 kB
| |
| MemFree: 6533108 kB
| |
| MemAvailable: 7010340 kB
| |
| Buffers: 68588 kB
| |
| Cached: 589804 kB
| |
| SwapCached: 0 kB
| |
| Active: 1032108 kB
| |
| Inactive: 398668 kB
| |
| Active(anon): 774636 kB
| |
| Inactive(anon): 26916 kB
| |
| Active(file): 257472 kB
| |
| Inactive(file): 371752 kB
| |
| Unevictable: 32 kB
| |
| Mlocked: 32 kB
| |
| SwapTotal: 3905532 kB
| |
| SwapFree: 3905532 kB
| |
| Dirty: 120 kB
| |
| Writeback: 0 kB
| |
| AnonPages: 772420 kB
| |
| Mapped: 237016 kB
| |
| Shmem: 29172 kB
| |
| Slab: 66140 kB
| |
| SReclaimable: 33900 kB
| |
| SUnreclaim: 32240 kB
| |
| KernelStack: 7648 kB
| |
| PageTables: 26308 kB
| |
| NFS_Unstable: 0 kB
| |
| Bounce: 0 kB
| |
| WritebackTmp: 0 kB
| |
| CommitLimit: 7969548 kB
| |
| Committed_AS: 3499748 kB
| |
| VmallocTotal: 34359738367 kB
| |
| VmallocUsed: 132284 kB
| |
| VmallocChunk: 34359549692 kB
| |
| HardwareCorrupted: 0 kB
| |
| AnonHugePages: 188416 kB
| |
| CmaTotal: 0 kB
| |
| CmaFree: 0 kB
| |
| HugePages_Total: 0
| |
| HugePages_Free: 0
| |
| HugePages_Rsvd: 0
| |
| HugePages_Surp: 0
| |
| Hugepagesize: 2048 kB
| |
| DirectMap4k: 124544 kB
| |
| DirectMap2M: 8216576 kB
| |
| | |
| etienne@etienne-ThinkPad-W520: ~/Documents lspci -t -v -nn
| |
| -[0000:00]-+-00.0 Intel Corporation 2nd Generation Core Processor Family DRAM Controller [8086:0104]
| |
| +-01.0-[01]--+-00.0 NVIDIA Corporation GF106GLM [Quadro 2000M] [10de:0dda]
| |
| | \-00.1 NVIDIA Corporation GF106 High Definition Audio Controller [10de:0be9]
| |
| +-16.0 Intel Corporation 6 Series/C200 Series Chipset Family MEI Controller #1 [8086:1c3a]
| |
| +-16.3 Intel Corporation 6 Series/C200 Series Chipset Family KT Controller [8086:1c3d]
| |
| +-19.0 Intel Corporation 82579LM Gigabit Network Connection [8086:1502]
| |
| +-1a.0 Intel Corporation 6 Series/C200 Series Chipset Family USB Enhanced Host Controller #2 [8086:1c2d]
| |
| +-1b.0 Intel Corporation 6 Series/C200 Series Chipset Family High Definition Audio Controller [8086:1c20]
| |
| +-1c.0-[02]--
| |
| +-1c.1-[03]----00.0 Intel Corporation Centrino Ultimate-N 6300 [8086:4238]
| |
| +-1c.3-[05-0c]--
| |
| +-1c.4-[0d]--+-00.0 Ricoh Co Ltd PCIe SDXC/MMC Host Controller [1180:e823]
| |
| | \-00.3 Ricoh Co Ltd R5C832 PCIe IEEE 1394 Controller [1180:e832]
| |
| +-1c.6-[0e]----00.0 NEC Corporation uPD720200 USB 3.0 Host Controller [1033:0194]
| |
| +-1d.0 Intel Corporation 6 Series/C200 Series Chipset Family USB Enhanced Host Controller #1 [8086:1c26]
| |
| +-1f.0 Intel Corporation QM67 Express Chipset Family LPC Controller [8086:1c4f]
| |
| +-1f.2 Intel Corporation 6 Series/C200 Series Chipset Family 6 port SATA AHCI Controller [8086:1c03]
| |
| \-1f.3 Intel Corporation 6 Series/C200 Series Chipset Family SMBus Controller [8086:1c22]
| |
| | |
| etienne@etienne-ThinkPad-W520: ~/Documents lsusb
| |
| Bus 004 Device 003: ID 0bdb:1911 Ericsson Business Mobile Networks BV
| |
| Bus 004 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub
| |
| Bus 004 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
| |
| Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
| |
| Bus 001 Device 002: ID 046d:c515 Logitech, Inc. Cordless 2.4 GHz Presenter Presentation remote control
| |
| Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
| |
| Bus 003 Device 006: ID 04f2:b217 Chicony Electronics Co., Ltd Lenovo Integrated Camera (0.3MP)
| |
| Bus 003 Device 004: ID 147e:2016 Upek Biometric Touchchip/Touchstrip Fingerprint Sensor
| |
| Bus 003 Device 003: ID 0765:5001 X-Rite, Inc. Huey PRO Colorimeter
| |
| Bus 003 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub
| |
| | |
| I am running the Ubuntu version 14.04.3 LTS distribution of Linux.
| |
| The running OS kernel is Linux 3.19.0-25-generic.
| |
| My CPU is an Intel(R) Core(TM) i7-2860QM CPU @ 2.50GHz. It has 4 cores.
| |
| The CPU architecture is x86_64: so 64-bit.
| |
| The RAM is a bit more than 8Gb big.
| |
| Connected to the PCI devices, there is some DRAM, the graphic card (Nvidia), some unknown controllers (MEI and KT), the Gigabit port card, 2 USB ports, Wireless card (Intel centrino), a SD card port, a Sata port.
| |
| Regarding the USB devices, I can see the port for the sim card, the camera of the computer, the fingerprint sensor.
| |
| The fdisk command did not output anything so I used cat /proc/partitions instead. It shows 7 partitions (+ one for the CD/DVD drive): 3 for Windows and 3 for Ubuntu.
| |
| The screen shows a resolutions of minimum of 320 x 200, maximum 8192 x 8192. The currently used is 1920 x 1080.
| |
| The wireless network interface is detected, as well as the Bluetooth device (after I turn it ON).
| |
| The glxinfo command outputs something really long and not understandable.
| |
| The computer has two audio cards: one buit-in from Intel, and one from Nvidia. Nvidia uses the bus 01.0/00.1 and the Intel one uses the bus 1b.0
| |
| The graphic controller is from Nvidia on bus 01.00/00.0
| |
| The Lenovo integrated camera is on bus 3.
| |
| The wired network chipset is 82579LM Gigabit Network Connection from Intel. It is on bus 19.0
| |
| The wireless network chipset is Intel Centrino Ultimate-N 6300 on bus 1c.1.
| |
| I cannot identify the bluetooth device.
| |
| I think there is a cellular modem connected under "Ericsson Business Mobile Networks" on bus 4.
| |
| | |
| ¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤
| |
| | |
| 1 def fib(n):
| |
| 2 a,b = 1,1
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| 3 for i in range(n-1):
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| 4 a,b = b,a+b
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| 5 return a
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| | |
| | |
| 2 0 LOAD_CONST 2 ((1, 1)) Constants of 1 and 1 are pushed onto the stack
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| 3 UNPACK_SEQUENCE 2 Unpacks the top-of-stack (TOS) into count individual values, which are put onto the stack right-to-left
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| 6 STORE_FAST 1 (a) Stores TOS into the local variable a
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| 9 STORE_FAST 2 (b) Stores TOS into the local variable b
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|
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| 3 12 SETUP_LOOP 41 (to 56) Loop until line 56 is set up
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| 15 LOAD_GLOBAL 0 (range) Loads a global range for the loop
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| 18 LOAD_FAST 0 (n) Pushes a reference to the local variable n onto the stack
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| 21 LOAD_CONST 1 (1) Pushes the constant 1 onto the stack
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| 24 BINARY_SUBTRACT Implements TOS = TOS1 - TOS. Subtraction of (n-1)
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| 25 CALL_FUNCTION 1 Calls a function
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| 28 GET_ITER Implements the iteration on TOS
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| >> 29 FOR_ITER 23 (to 55) TOS is an operator and iteration is set up until line 55
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| 32 STORE_FAST 3 (i) Stores TOS into local variable i
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|
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| 4 35 LOAD_FAST 2 (b) Pushes a reference to the local variable b onto the stack
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| 38 LOAD_FAST 1 (a) Pushes a reference to the local variable a onto the stack
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| 41 LOAD_FAST 2 (b) Pushes a reference to the local variable b onto the stack
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| 44 BINARY_ADD Implements TOS = TOS1 + TOS. Addition of (a+n)
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| 45 ROT_TWO Swaps the two top-most stack items. TOS1 = a+b. TOS = b
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| 46 STORE_FAST 1 (a) Stores TOS into local variable a
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| 49 STORE_FAST 2 (b) Stores TOS into local variable b
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| 52 JUMP_ABSOLUTE 29 Set bytecode counter to target
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| >> 55 POP_BLOCK End of the iteration
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|
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| 5 >> 56 LOAD_FAST 1 (a) Pushes a reference to the local variable a onto the stack
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| 59 RETURN_VALUE Returns the value of TOS
| |
| | |
| | |
| 1
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| 2 def fib(n):
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| 3 a,b = 1,1
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| 4 for i in range(n-1):
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| 5 a,b = b,a+b
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| 6 return a
| |
| | |
| fib(3) => see below
| |
| 3 0 LOAD_CONST 2 ((1, 1)) Stack = [(1, 1)]
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| 3 UNPACK_SEQUENCE 2 Stack = [(1, 1)]
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| 6 STORE_FAST 1 (a) Stack =[]; co_varnames = [a=1]
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| 9 STORE_FAST 2 (b) Stack =[]; co_varnames = [a=1, b=1]
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|
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| 4 12 SETUP_LOOP 41 (to 56) Stack = []; loop is set up, counter is 1
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| 15 LOAD_GLOBAL 0 (range) Stack = []
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| 18 LOAD_FAST 0 (n) Stack = [n=3]
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| 21 LOAD_CONST 1 (1) Stack = [1, n=3]
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| 24 BINARY_SUBTRACT Stack = [n-1=2]
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| 25 CALL_FUNCTION 1
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| 28 GET_ITER
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| >> 29 FOR_ITER 23 (to 55) Iteration at 1
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| 32 STORE_FAST 3 (i) Stack = []; co_varnames = [a=1, b=1, i=1]
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| 5 35 LOAD_FAST 2 (b) Stack = [b=1]
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| 38 LOAD_FAST 1 (a) Stack = [a=1, b=1]
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| 41 LOAD_FAST 2 (b) Stack = [b=1, a=1, b=1]
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| 44 BINARY_ADD Stack = [b=1+a=1, b=1]
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| 45 ROT_TWO Stack = [b=1, 2]
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| 46 STORE_FAST 1 (a) Stack = []; co_varnames = [a=1, b=1, i=1]
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| 49 STORE_FAST 2 (b) Stack = []; co_varnames = [a=1, b=2, i=1]
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| 52 JUMP_ABSOLUTE 29 Jump to 29
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|
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| >> 29 FOR_ITER 23 (to 55) Iteration at 2
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| 32 STORE_FAST 3 (i) Stack = []; co_varnames = [a=1, b=2, i=2]
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| 5 35 LOAD_FAST 2 (b) Stack = [b=2]
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| 38 LOAD_FAST 1 (a) Stack = [a=1, b=1]
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| 41 LOAD_FAST 2 (b) Stack = [b=2, a=1, b=2]
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| 44 BINARY_ADD Stack = [b=2+a=1, b=2]
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| 45 ROT_TWO Stack = [b=2, 3]
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| 46 STORE_FAST 1 (a) Stack = []; co_varnames = [a=1, b=2, i=2]
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| 49 STORE_FAST 2 (b) Stack = []; co_varnames = [a=2, b=3, i=2]
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| 52 JUMP_ABSOLUTE 29 Jump to 29
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|
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| >> 29 FOR_ITER 23 (to 55) Iteration at 3 => jumps to instructions 55
| |
|
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| >> 55 POP_BLOCK Ends the loop
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|
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| 6 >> 56 LOAD_FAST 1 (a) Stack = [a=2]
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| 59 RETURN_VALUE Stack = [2]
| |
| | |
| ¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤
| |
| | |
| int fib(n) {
| |
| int a = 1;
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| int b = 1;
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| int i;
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| for (i = 0; i < n; i++) {
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| int s = a + b;
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| a = b;
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| b = s;
| |
| }
| |
| return a;
| |
| }
| |
| | |
| General code description
| |
| | |
| fib:
| |
| mov r3, #1 /Copy constant #1 to register 3 /Gives the constant value "1" to b in r3
| |
| mov r1, #0 /Copy constant #0 to register 1 /Gives the constant value "0" to i in r1
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| mov r2, r3 /Copy value in register 3 to register 2 /Gives the value "1" of b to a in r2
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| b .L2 /Jump to .L2 /Jump to L2
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|
| |
| .L3: /Execution of the loop operations
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| add ip, r2, r3 /ip = r2 + r3 /s(ip) = b(r3) + a(r2)
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| add r1, r1, #1 /r1 = r1 + constant #1 /i(r1) = i(r1) + 1(#1) this is the iteration i++
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| mov r2, r3 /copy r3 to r2 /b(r3) gives its value to a(r2)
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| mov r3, ip /copy ip to r3 /s(ip) gives its value to b(r3)
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|
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| .L2: /Condition of the loop
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| cmp r1, r0 /compare r0 against r1 /Tells if i(r1) equals n (r0)
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| blt .L3 /jumps to .L3 if comparison above is "not equal" /jumps to .L3 if comparison above is "not equal"
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| mov r0, r2 /copy r2 to r0 /0 in r0 gets its value replaces by a(r2). This is the return statement
| |
| bx lr /jump back to caller /
| |
| | |
| | |
| With 3 as argument, step by step instructions
| |
| | |
| fib:
| |
| mov r3, #1 /Gives the constant value "1" to b in r3
| |
| mov r1, #0 /Gives the constant value "0" to i in r1
| |
| mov r2, r3 /Gives the value "1" of b to a in r2
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| b .L2 /Jump to .L2
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|
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| .L2: /Loop
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| cmp r1, r0 /Tells if i=0(r1) equals n=3(r0)
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| blt .L3 /jumps to .L3 as comparison above is "not equal" 0!=3
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|
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| .L3: /Execution of the loop operations
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| add ip, r2, r3 /s=2(ip) = b=1(r3) + a=1(r2)
| |
| add r1, r1, #1 /i=1(r1) = i=0(r1) + 1(#1) this is the iteration i++
| |
| mov r2, r3 /b=1(r3) gives its value to a=1(r2)
| |
| mov r3, ip /s=2(ip) gives its value to b=2(r3)
| |
|
| |
| .L2: /Loop
| |
| cmp r1, r0 /Tells if i=1(r1) equals n=3(r0)
| |
| blt .L3 /jumps to .L3 as comparison above is "not equal" 1!=3
| |
|
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| .L3: /Execution of the loop operations
| |
| add ip, r2, r3 /s=3(ip) = b=2(r3) + a=1(r2)
| |
| add r1, r1, #1 /i=2(r1) = i=1(r1) + 1(#1) this is the iteration i++
| |
| mov r2, r3 /b=2(r3) gives its value to a=2(r2)
| |
| mov r3, ip /s=3(ip) gives its value to b=3(r3)
| |
|
| |
| .L2: /Loop
| |
| cmp r1, r0 /Tells if i=2(r1) equals n=3(r0)
| |
| blt .L3 /jumps to .L3 as comparison above is "not equal" 2!=3
| |
|
| |
| .L3: /Execution of the loop operations
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| add ip, r2, r3 /s=5(ip) = b=3(r3) + a=2(r2)
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| add r1, r1, #1 /i=3(r1) = i=2(r1) + 1(#1) this is the iteration i++
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| mov r2, r3 /b=3(r3) gives its value to a=3(r2)
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| mov r3, ip /s=5(ip) gives its value to b=5(r3)
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| .L2: /Loop
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| cmp r1, r0 /Tells if i=3(r1) equals n=3(r0) => 3=3 end of loop
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| mov r0, r2 /r0=3 gets its value from a=3(r2). This is the return statement.
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| bx lr /
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| At this point the values left in registers are: r0=3, r1=3, r2=3, r3=5, ip=5
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| Code examples
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| MOV r4, #10 /* r4 = 10 */
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| .loop-label: /* Offset in code */
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| BL do_something /* Call */
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| SUB r4, r4, #1 /* r4 = r4 - 1 */
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| CMP r4, #0 /* r4 <> 0 */
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| BNE loop-label /* Branch if not equal */
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| MOV r0, #10 /* 1st arg is 10 */
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| MOV r1, #20 /* 2nd arg is 20 */
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| BL function-label /* Jump to func. This stores pc+4 in lr */
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| MOV r4, r0 /* Result at r0 */
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| .function-label: /* Offset in code */
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| ADD r4, r0, r1 /* r4 = r0 + r1 */
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| MUL r0, r4, r1 /* r0 = r4 * r1 */
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| B lr /* Jump to caller */
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