diff options
Diffstat (limited to 'cpu/registers/config.txt')
| -rw-r--r-- | cpu/registers/config.txt | 50 |
1 files changed, 50 insertions, 0 deletions
diff --git a/cpu/registers/config.txt b/cpu/registers/config.txt new file mode 100644 index 0000000..2be32a1 --- /dev/null +++ b/cpu/registers/config.txt @@ -0,0 +1,50 @@ +MR (Mode Register) + CPU mode (16-bit, 32-bit, 64-bit, etc) + + Adjusts size according to current CPU mode + + On read + Gives supported modes + If ((1 << ([desired mode in bytes] - 1)) & cr0) != 0, then it is supported + + Support for 16-bit mode, 64-bit mode, 128-bit mode, and 256 bit mode would be represented as 111010b + + On write + Sets current mode + Follows the same pattern as reading + 100b would represent 32-bit mode + + Only one bit is allowed to be set + Triggers <TODO> exception otherwise + + No need for a jump instruction immediately after it + +PR (Privilege Register) + Consists of flags for specific privileges + Bit 0: Can configure everything + All other bits are to be configured at runtime + + CPU initializes with it set to all 1s + Always readable + Writing directly is only allowed to remove permissions + Triggers <TODO> exception otherwise + + Additional privileges can be granted by interrupts, exceptions and IRQs as configured by the IDT, EDT and IRQT, respectively + +FR (Feature Register) + Consists of various bit flags for different features that are currently enabled + + See features/all.txt for a full list + + Read only + +OFR (Optional Feature Register) + Consists of various bit flags for different features that can be enabled/disabled at runtime + + See features/all.txt for a full list + + On read: + Lists features that can be enabled/disabled + + On write: + Sets the configurable features, and ignores bits for non-configurable ones |