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81 lines
2.4 KiB
Markdown
81 lines
2.4 KiB
Markdown
---
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title: Memory Access
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weight: 30
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pre: ""
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chapter: false
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---
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## read / readWord ##
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**Syntax**
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emu.read(address, type, signed = false)
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emu.readWord(address, type, signed = false)
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**Parameters**
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address - *Integer* The address/offset to read from.
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type - *Enum* The type of memory to read from. See [memType](/apireference/enums.html#memtype).
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signed - (optional) *Boolean* If true, the value returned will be interpreted as a signed value.
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**Return value**
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An 8-bit (read) or 16-bit (readWord) value.
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**Description**
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Reads a value from the specified [memory type](/apireference/enums.html#memtype).
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When calling read / readWord, it is possible to trigger side-effects (such as register reads) when not using the "debug" memory types.
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To avoid triggering side-effects, use the "debug" memory types.
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## write / writeWord ##
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**Syntax**
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emu.write(address, value, type)
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emu.writeWord(address, value, type)
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**Parameters**
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address - *Integer* The address/offset to write to.
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value - *Integer* The value to write.
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type - *Enum* The type of memory to write to. See [memType](/apireference/enums.html#memtype).
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**Return value**
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*None*
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**Description**
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Writes an 8-bit or 16-bit value to the specified [memory type](/apireference/enums.html#memtype).
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Read-only memory such as PRG ROM can be written to using write/writeWord. Changes will remain in effect until the ROM is reloaded.
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When calling write / writeWord, it is possible to trigger side-effects (such as register writes) when not using the "debug" memory types.
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To avoid triggering side-effects, use the "debug" memory types.
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## getPrgRomOffset ##
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**Syntax**
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emu.getPrgRomOffset(address)
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**Parameters**
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address - *Integer* A CPU address (Valid range: $0000-$FFFFFF)
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**Return value**
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*Integer* The corresponding byte offset in PRG ROM
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**Description**
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Returns an integer representing the byte offset of the specified CPU address in PRG ROM based on the mapper's current configuration. Returns -1 when the specified address is not mapped to PRG ROM.
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## getLabelAddress ##
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**Syntax**
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emu.getLabelAddress(label)
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**Parameters**
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label - *String* The label to look up
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**Return value**
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*Integer* The corresponding CPU address
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**Description**
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Returns the address of the specified label. This address can be used with the memory read/write functions (`read()`, `readWord()`, `write()`, `writeWord()`) using the `emu.memType.cpu` or `emu.memType.cpuDebug` memory types.
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