Difference between revisions of "LDX"

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This pseudo C code shows how the LDX opcode functions when it is executed.
 
This pseudo C code shows how the LDX opcode functions when it is executed.
  
  SET_NEGATIVE(Operand);        // Clears the [[Negative Flag]] if the Operand is $#00-7F, otherwise sets it.
+
  SET_NEGATIVE(Operand);        // Sets the [[Negative Flag]] equal to the 7th bit.
 
  SET_ZERO(Operand);            // Sets the [[Zero Flag]] if the Operand is $#00, otherwise clears it.
 
  SET_ZERO(Operand);            // Sets the [[Zero Flag]] if the Operand is $#00, otherwise clears it.
 
  X_INDEX = Operand;            // Stores the Operand in the X Index Register.
 
  X_INDEX = Operand;            // Stores the Operand in the X Index Register.
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==Addressing Modes==
 
==Addressing Modes==
 
{{OpcodeHeader}}
 
{{OpcodeHeader}}
{{OpcodeLine|Immediate|LDX ''#Operand''|A1|2|2}}
+
{{OpcodeLine|Immediate|LDX ''#Operand''|A2|2|2}}
 
{{OpcodeLine|Zero Page|LDX ''Operand''|A6|2|3}}
 
{{OpcodeLine|Zero Page|LDX ''Operand''|A6|2|3}}
 
{{OpcodeLine|Zero Page, X|LDX ''Operand, X''|B6|2|4}}
 
{{OpcodeLine|Zero Page, X|LDX ''Operand, X''|B6|2|4}}

Latest revision as of 08:20, 1 December 2017

Load X Index With Memory
Opcode: LDX
Operation: M → X
Status Register: Status-List.png
Status-Change.pngStatus-Space.pngStatus-Change.pngStatus-Space.pngStatus-Ignore.pngStatus-Space.pngStatus-Ignore.pngStatus-Space.pngStatus-Ignore.pngStatus-Space.pngStatus-Ignore.png

LDX (Load X Index With Memory) loads the X Index Register with the specified memory. It is similar in function to LDA and LDY opcodes. Unlike LDA, there aren't as many addressing modes available for LDX.

Operation

This pseudo C code shows how the LDX opcode functions when it is executed.

SET_NEGATIVE(Operand);        // Sets the Negative Flag equal to the 7th bit.
SET_ZERO(Operand);            // Sets the Zero Flag if the Operand is $#00, otherwise clears it.
X_INDEX = Operand;            // Stores the Operand in the X Index Register.

Addressing Modes

Addressing Mode Assembly Language Form Opcode # Bytes # Cycles
Immediate LDX #Operand A2 2 2
Zero Page LDX Operand A6 2 3
Zero Page, X LDX Operand, X B6 2 4
Absolute LDX Operand AE 3 4
Absolute, X LDX Operand, X BE 3 4*
* Add 1 if page boundary is crossed.

Examples