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Diffstat (limited to 'mips.html.markdown')
| -rw-r--r-- | mips.html.markdown | 101 |
1 files changed, 72 insertions, 29 deletions
diff --git a/mips.html.markdown b/mips.html.markdown index e40c4b64..6a9a7c2a 100644 --- a/mips.html.markdown +++ b/mips.html.markdown @@ -5,7 +5,10 @@ contributors: - ["Stanley Lim", "https://github.com/Spiderpig86"] --- -The MIPS (Microprocessor without Interlocked Pipeline Stages) Assembly language is designed to work with the MIPS microprocessor paradigm designed by J. L. Hennessy in 1981. These RISC processors are used in embedded systems such as gateways and routers. +The MIPS (Microprocessor without Interlocked Pipeline Stages) Assembly language +is designed to work with the MIPS microprocessor paradigm designed by J. L. +Hennessy in 1981. These RISC processors are used in embedded systems such as +gateways and routers. [Read More](https://en.wikipedia.org/wiki/MIPS_architecture) @@ -16,14 +19,18 @@ The MIPS (Microprocessor without Interlocked Pipeline Stages) Assembly language # Programs typically contain a .data and .text sections -.data # Section where data is stored in memory (allocated in RAM), similar to variables in higher level languages +.data # Section where data is stored in memory (allocated in RAM), similar to +variables in higher level languages # Declarations follow a ( label: .type value(s) ) form of declaration hello_world .asciiz "Hello World\n" # Declare a null terminated string - num1: .word 42 # Integers are referred to as words (32 bit value) + num1: .word 42 # Integers are referred to as words + # (32 bit value) + arr1: .word 1, 2, 3, 4, 5 # Array of words arr2: .byte 'a', 'b' # Array of chars (1 byte each) - buffer: .space 60 # Allocates space in the RAM (not cleared to 0) + buffer: .space 60 # Allocates space in the RAM + # (not cleared to 0) # Datatype sizes _byte: .byte 'a' # 1 byte @@ -32,34 +39,62 @@ hello_world .asciiz "Hello World\n" # Declare a null terminated string _float: .float 3.14 # 4 bytes _double: .double 7.0 # 8 bytes - .align 2 # Memory alignment of data, where number indicates byte alignment in powers of 2. (.align 2 represents word alignment since 2^2 = 4 bytes) + .align 2 # Memory alignment of data, where + # number indicates byte alignment in + # powers of 2. (.align 2 represents + #word alignment since 2^2 = 4 bytes) -.text # Section that contains instructions and program logic -.globl _main # Declares an instruction label as global, making it accessible to other files +.text # Section that contains instructions + # and program logic +.globl _main # Declares an instruction label as + # global, making it accessible to + # other files - _main: # MIPS programs execute instructions sequentially, where the code under this label will be executed firsts + _main: # MIPS programs execute instructions + # sequentially, where the code under + # this label will be executed firsts # Let's print "hello world" - la $a0, hello_world # Load address of string stored in memory - li $v0, 4 # Load the syscall value (indicating type of functionality) - syscall # Perform the specified syscall with the given argument ($a0) + la $a0, hello_world # Load address of string stored in + # memory + li $v0, 4 # Load the syscall value (indicating + # type of functionality) + syscall # Perform the specified syscall with + # the given argument ($a0) # Registers (used to hold data during program execution) - # $t0 - $t9 # Temporary registers used for intermediate calculations inside subroutines (not saved across function calls) - # $s0 - $s7 # Saved registers where values are saved across subroutine calls. Typically saved in stack - # $a0 - $a3 # Argument registers for passing in arguments for subroutines - # $v0 - $v1 # Return registers for returning values to caller function + # $t0 - $t9 # Temporary registers used for + # intermediate calculations inside + # subroutines (not saved across + # function calls) + + # $s0 - $s7 # Saved registers where values are + # saved across subroutine calls. + # Typically saved in stack + + # $a0 - $a3 # Argument registers for passing in + # arguments for subroutines + # $v0 - $v1 # Return registers for returning + # values to caller function # Types of load/store instructions - la $t0, label # Copy the address of a value in memory specified by the label into register $t0 + la $t0, label # Copy the address of a value in + # memory specified by the label into + # register $t0 lw $t0, label # Copy a word value from memory - lw $t1, 4($s0) # Copy a word value from an address stored in a register with an offset of 4 bytes (addr + 4) - lb $t2, label # Copy a byte value to the lower order portion of the register $t2 - lb $t2, 0($s0) # Copy a byte value from the source address in $s0 with offset 0 + lw $t1, 4($s0) # Copy a word value from an address + # stored in a register with an offset + # of 4 bytes (addr + 4) + lb $t2, label # Copy a byte value to the lower order + # portion of the register $t2 + lb $t2, 0($s0) # Copy a byte value from the source + # address in $s0 with offset 0 # Same idea with 'lh' for halfwords - sw $t0, label # Store word value into memory address mapped by label - sw $t0, 8($s0) # Store word value into address specified in $s0 and offset of 8 bytes + sw $t0, label # Store word value into memory address + # mapped by label + sw $t0, 8($s0) # Store word value into address + # specified in $s0 and offset of 8 bytes # Same idea using 'sb' and 'sh' for bytes and halfwords. 'sa' does not exist ### Math ### @@ -71,16 +106,24 @@ hello_world .asciiz "Hello World\n" # Declare a null terminated string add $t2, $t0, $t1 # $t2 = $t0 + $t1 sub $t2, $t0, $t1 # $t2 = $t0 - $t1 mul $t2, $t0, $t1 # $t2 = $t0 * $t1 - div $t2, $t0, $t1 # $t2 = $t0 / $t1 (Might not be supported in some versons of MARS) - div $t0, $t1 # Performs $t0 / $t1. Get the quotient using 'mflo' and remainder using 'mfhi' + div $t2, $t0, $t1 # $t2 = $t0 / $t1 (Might not be + # supported in some versons of MARS) + div $t0, $t1 # Performs $t0 / $t1. Get the quotient + # using 'mflo' and remainder using 'mfhi' # Bitwise Shifting - sll $t0, $t0, 2 # Bitwise shift to the left with immediate (constant value) of 2 - sllv $t0, $t1, $t2 # Shift left by a variable amount in register - srl $t0, $t0, 5 # Bitwise shift to the right (does not sign preserve, sign-extends with 0) - srlv $t0, $t1, $t2 # Shift right by a variable amount in a register - sra $t0, $t0, 7 # Bitwise arithmetic shift to the right (preserves sign) - srav $t0, $t1, $t2 # Shift right by a variable amount in a register + sll $t0, $t0, 2 # Bitwise shift to the left with + # immediate (constant value) of 2 + sllv $t0, $t1, $t2 # Shift left by a variable amount in + # register + srl $t0, $t0, 5 # Bitwise shift to the right (does + # not sign preserve, sign-extends with 0) + srlv $t0, $t1, $t2 # Shift right by a variable amount in + # a register + sra $t0, $t0, 7 # Bitwise arithmetic shift to the right + # (preserves sign) + srav $t0, $t1, $t2 # Shift right by a variable amount + # in a register # Bitwise operators and $t0, $t1, $t2 # Bitwise AND |