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Doc: Decide on opcode mnemonics

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Riyyi
2022-08-23 23:08:21 +02:00
parent e2ca4359f2
commit fe020c9374
1 changed files with 20 additions and 10 deletions
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doc/terminology.org
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@@ -11,26 +11,33 @@ GameBoy terminology.
| Name | Modern equivalent | Description |
|-----------------+-------------------+-------------------------------------------|
| APU | | Audio Processing Unit |
| APU | Sound card | Audio Processing Unit |
| PPU | GPU | Pixel Processing Unit |
| Bootrom | BIOS | |
| HRAM (High RAM) | CPU cache | Embedded memory inside the CPU, 127 bytes |
| WRAM (Work RAM) | RAM | |
*** Flags
The Half Cary (H) flag differs between 8-bit or 16-bit operations. The 8-bit
variant indicates carry for the lower 4 bits of the result, or overflow from bit
4 to bit 5. The 16-bit variant indicates carry for the lower 4 bits of the
*second* byte of the result, or overflow from bit 12 to bit 13.
*** Opcode
| Name | Bits | Sign | Mnemonics | [[https://gbdev.io/gb-opcodes/optables/][1]] | [[https://rgbds.gbdev.io/docs/v0.5.2/gbz80.7/][2]] | [[https://gekkio.fi/files/gb-docs/gbctr.pdf][3]]/[[http://marc.rawer.de/Gameboy/Docs/GBCPUman.pdf][3]] | [[https://gbdev.io/pandocs/CPU_Instruction_Set.html][4]] | Description | Note |
|-----------+------+----------+-----------+------+-----+------+-----+------------------------------+-------------------|
| | | | | <r> | <r> | <r> | <r> | | |
| immediate | 8 | unsigned | | d8 | n8 | n | | Next byte in memory | |
| immediate | 16 | unsigned | | d16 | n16 | nn | | Next byte in memory | little-endian |
| register | 8 | unsigned | | | r8 | r | | Any of the registers | |
| register | 16 | unsigned | | | r16 | rr | | Any of the registers | little-endian |
| address | 8 | unsigned | | | | (n) | | Address at value | |
| address | 16 | unsigned | | a16 | n16 | (nn) | nn | Address at value | little-endian |
| immediate | 8 | signed | | r8 | e8 | e | dd | Next byte in memory | |
| immediate | 8 | unsigned | | (a8) | n16 | (n) | n | 0xff00 + next byte in memory | write to I/O-port |
| condition | | | | NZ | cc | | f | Execute if condition met | |
| immediate | 8 | unsigned | i8 | d8 | n8 | n | | Next byte in memory | |
| immediate | 16 | unsigned | i16 | d16 | n16 | nn | | Next byte in memory | little-endian |
| register | 8 | unsigned | r8 | | r8 | r | | Any of the registers | |
| register | 16 | unsigned | r16 | | r16 | rr | | Any of the registers | little-endian |
| address | 8 | unsigned | a8 | | | (n) | | Address at value | |
| address | 16 | unsigned | a16 | a16 | n16 | (nn) | nn | Address at value | little-endian |
| immediate | 8 | signed | s8 | r8 | e8 | e | dd | Next byte in memory | |
| immediate | 8 | unsigned | io8 | (a8) | n16 | (n) | n | 0xff00 + next byte in memory | write to I/O-port |
| condition | | | <ZNHC> | NZ | cc | | f | Execute if condition met | |
d = data \\
n = constant
@@ -41,6 +48,9 @@ n = constant
|--------+--------------------|
| length | amount of elements |
| size | amount of bytes |
|--------+--------------------|
| lhs | left hand side |
| rhs | right hand side |
** References