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Questions tagged [immediate-operand]

94 questions
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In a MIPS assembly `addi` instruction, how is a hexadecimal immediate interpreted?

Is there is a standard or recommendation for how the addi instruction (and others) should be interpreted in assembly, when hexadecimal immediate values are used? Example: addi $t0, $zero, 0xffff I was expecting this to mean the same as addi $t0,…
Miguel
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Can I add 64bit constants to 64bit registers?

At my 64bit Intel machine following code works: mov rdi, 1 << 40 add r10, rdi and this quite equivalent looking one produces a warning and doesn't work: add r10, 1 << 40 Should I just stick with number 1 or am I missing something? This behaviour…
user1864035
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GCC seems to prefer small immediate values in comparisons. Is there a way to avoid that?

Firstly a trivial mathematical fact: given integers n and m, we have n < m if, and only if, n <= m - 1. GCC seems to prefer immediate values of smaller absolute value. Hence, when m is known and other conditions are met, the compiler chooses among…
Cassio Neri
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Why isn't # needed before numbers with DC.W (Define Constant), only instructions?

I have this line of code: X DC.W 5 This means basically X = 5 But shouldn't be X DC.W #5 ? When using MOVE I need always # MOVE.B #1,VAR
dynamic
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How does LUI/ORI on MIPS work to create a 32-bit constant value?

I have this risc v code : lui S0, 0x1234 ori S1, S0, 0x5678 add S2, S1, S1 and the question asks me, "What does the register S2 hold?" The question explains that lui and I quote: "Load the lower half word of the immediate imm into the upper…
Razi Awad
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Why doesn't MIPS have a Store Immediate instruction just like Load Immediate instruction?

MIPS has a Load Immediate (LI) pseudo instruction to load a 32-bit immediate value into a register. But it does not have Store Immediate (SI) instruction to store a 32-bit immediate value to Memory. Can someone explain me why?
sandywho
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In MIPS, when to use a signed-extend, when to use a zero-extend?

I am designing a MIPS processor as my individual project, by now I met a very confused question. I just can not summarize when to use signed-extend and when to use zero-extend in MIPS. I have searched lots of resources, mostly said: 1) ADDI, ADDIU…
Shuaiyu Jiang
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Literals VS Immediate Operands

In the systems software course that I have this semester, we are being taught assemblers and other system software. While reading across the course I came across the topic of LITERALS. There was a comparison between literals and immediate operands…
Crystal Meth
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How to add an immediate byte to a long register with AT&T syntax on x86?

From what I understand reading the Intel manuals, it should be possible to write an instruction like add $0x7f, %ebx and it should be encoded as 83 /0 ib for a total of three bytes. However, when I do this (whether I use add, addb, or addl) it…
user1084743
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GNU assembler override size of immediate operand

I am trying to match a specific sequence of bytes with GNU assembler. Objdump disassembles these bytes as: 81 e2 66 00 00 00 and edx,0x66 However, GAS "helpfully" assembles this instruction more efficiently: 83 e2 66 and …
rtburns
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Using the blend instructions in intel intrinsics (AVX)

I have a question regarding the AVX _mm256_blend_pd function. I want to optimize my code where I use heavily the _mm256_blendv_pd function. This unfortunately has a pretty high latency and low throughput. This function takes as input three __m256d…
DevX10
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Translate the following machine language code (0x2237FFF1) into MIPS assembly

I have translate this code so far and what I'm not understanding is how to figure out (calculate)the amount of 16-bit immediate address. 0x2237FFF1 To binary 0010 0010 0011 0111 1111 1111 1111 0001 Now I'm reading the opcode (001000) and know that…
Adam
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Specifying 8bit immediate in x86-64 (GNU Assembler)

I'm trying to write some special routine in assembly, for x86-64 (even x86 example is fine). The problem: my immediates are only resolved at link time. For example, addq $Label2-Label1, %rax will add the difference between the two labels/symbols to…
kktsuri
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What's difference between number with $ or without $ symbol in at&t assembly syntax?

Let's say .data section has following item: 0x1234 00010203 04050607 08090a0b 0c0d0e0f 0x1238 10000000 And in code, mov $0x1234, %eax mov 0x1238, %ebx I believe with $ symbol, it would be constant number, so %eax will have memory address, but what…
REALFREE
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How to encode immediate value in arm?

Suppose there is an inst like this: add ip, ip, #0x5000 the machine code is 05 CA 8C E2 and E2 8C CA 05 = 11100010100011001100 1010 00000101 imm = rotate_right(101B, 1010B*2) = 0x5000 But if we know 0x5000, how can we get 101000000101?…
scvyao
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