GB Programming: Difference between revisions
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m (Text replacement - "(\bld(?:|i|l|d|h) (?:.+, ?)?)\((.+)\)" to "$1[$2]") |
m (Text replacement - "(hl)" to "[hl]") |
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So now, how to access memory? With parentheses! To access memory address $CD38, you just have to use ($CD38). Yay! |
So now, how to access memory? With parentheses! To access memory address $CD38, you just have to use ($CD38). Yay! |
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To access the memory location pointed to by HL, just do... |
To access the memory location pointed to by HL, just do... [hl]! It's the same with BC and DE. |
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So, to retrieve the value at memory address $6511 into register A : ''ld a, [$6511]'' |
So, to retrieve the value at memory address $6511 into register A : ''ld a, [$6511]'' |
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| Line 494: | Line 494: | ||
!C |
!C |
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|- |
|- |
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|INC <nowiki>{reg8 | reg16 | |
|INC <nowiki>{reg8 | reg16 | [hl]}</nowiki> |
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|Adds one to the operand ("increments" it) |
|Adds one to the operand ("increments" it) |
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|Affected, except for reg16 |
|Affected, except for reg16 |
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|Not affected |
|Not affected |
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|- |
|- |
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|DEC <nowiki>{reg8 | reg16 | |
|DEC <nowiki>{reg8 | reg16 | [hl]}</nowiki> |
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|Subtracts one to the operand ("decrements" it) |
|Subtracts one to the operand ("decrements" it) |
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|Affected, except for reg16 |
|Affected, except for reg16 |
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|Not affected |
|Not affected |
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|- |
|- |
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|ADD A, <nowiki>{reg8 | imm8 | |
|ADD A, <nowiki>{reg8 | imm8 | [hl]}</nowiki> |
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|Adds the operand to the accumulator |
|Adds the operand to the accumulator |
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|Affected |
|Affected |
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| Line 514: | Line 514: | ||
|Not affected |
|Not affected |
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|- |
|- |
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|SUB <nowiki>{reg8 | imm8 | |
|SUB <nowiki>{reg8 | imm8 | [hl]}</nowiki> |
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|Subtracts the operand from the accumulator. The syntax SUB A, <nowiki>{...}</nowiki> is also valid but less common. |
|Subtracts the operand from the accumulator. The syntax SUB A, <nowiki>{...}</nowiki> is also valid but less common. |
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|Affected |
|Affected |
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| Line 582: | Line 582: | ||
ld b, [hl] |
ld b, [hl] |
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sub a, b |
sub a, b |
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inc |
inc [hl] |
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inc hl |
inc hl |
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ld [hl], b |
ld [hl], b |
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| Line 819: | Line 819: | ||
ld b, [hl] |
ld b, [hl] |
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</pre> |
</pre> |
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If |
If [hl] equals $63, execution jumps to placeItems. |
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Otherwise, executions continues through, increments hl twice, then jumps to "someplace" |
Otherwise, executions continues through, increments hl twice, then jumps to "someplace" |
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| Line 1,074: | Line 1,074: | ||
Notice here that doing ''sub a, b'' actually increased A's value! |
Notice here that doing ''sub a, b'' actually increased A's value! |
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inc |
inc [hl] ; (HL) = ($C004) = $DF |
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inc hl ; HL = $C005 |
inc hl ; HL = $C005 |
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