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# Vertex KISS 32 - Machine Code Spec
^ So Vertex is already a name for an FPGA, should we change this?
I propose a different name:
ASAP Soc 32 a KISS architecture
As
Simple
As
Possible
## General Instruction Format
X = HEX
B = BIN
MAX INSTRUCTIIONS = 256
ALL INSTRUCTIONS ARE ATOMIC
### C-Type, Control
XX X X XXXX
Opcode d RS1 IMM
### I-Type, Immediate
XX X X XXXX
Opcode RD RS1 IMM
### R-Type, Arithmetic
XX X X X XXX
Opcode RD RS1 RS2 ddd
### JR-Type, Compare and Jump
XX X X X XXX
Opcode Jump Condition RS1 RS2 ddd
### JI-Type, Compare and Jump
XX X X XXXX
Opcode Jump Condition RS1 IMM
## Registers
Maximum registers = 16
Register width = 32
All are R/W except 0X
0X Always Zero
AX GP-0
BX GP-1
CX GP-2
DX GP-3
EX GP-4
FX GP-5
GX GP-6
HX GP-7
IP Instruction Pointer
SP Stack Pointer
FLG Processor Flags
CS0 Control status 0 (saves IP)
CS1 Control status 1 (saves SP)
CS2 Control status 2 (saves FLG)
PDA Page Directory Address
### FLG Flag Register Bitfield
The lower half is read/write
The upper half can be read or written to in supervisor mode only
FLG[0] Carry
FLG[1] Overflow
FLG[2] Zero
FLG[3] Sign
FLG[4] Odd (might help with parity)
FLG[5-15] RESERVED
FLG[16] Interrupt enable*
FLG[17] User mode*
FLG[18] Paging enabled*
FLG[19-31] RESERVED*
*Must be in supervisor mode (FLG[17]=0) to set
## Integer Instructions
### R-Type
ADD RD, RS1, RS2 RD = RS1 + RS2
SUB RD, RS1, RS2 RD = RS1 - RS2
XOR RD, RS1, RS2 RD = RS1 ^ RS2
OR RD, RS1, RS2 RD = RS1 | RS2
AND RD, RS1, RS2 RD = RS1 & RS2
LSL RD, RS1, RS2 RD = RS1 << RS2 (logical)
LSR RD, RS1, RS2 RD = RS1 >> RS2 (logical)
ASR RD, RS1, RS2 RD = RS1 >> RS2
MUL RD, RS1, RS2 RD = RS1 * RS2
MULU RD, RS1, RS2 RD = RS1 * RS2 (unsigned)
DIV RD, RS1, RS2 RD = RS1 / RS2
DIVU RD, RS1, RS2 RD = RS1 / RS2 (unsigned)
*DIV is based on shift-and-multiply algorithm
*DIV Ex: 8000/192
(8000/64)/3
(8000>>6)/3
(8000>>6)*0x5555>>16=41
### I-Type
ADDI RD, RS, IMM RD = RS + IMM
SUBI RD, RS, IMM RD = RS - IMM
XORI RD, RS, IMM RD = RS ^ IMM
ORI RD, RS, IMM RD = RS | IMM
ANDI RD, RS, IMM RD = RS & IMM
LSLI RD, RS, IMM RD = RS << IMM (logical)
LSRI RD, RS, IMM RD = RS >> IMM (logical)
ASRI RD, RS, IMM RD = RS >> IMM
DIVI RD, RS, IMM RD = RS / IMM
DIVIU RD, RS, IMM RD = RS / IMM (unsigned)
### JR Instructions
JMP 0 if (True)
JMP 1 if (RS1 != RS2)
JMP 2 if (RS1 == RS2)
JMP 3 if (RS1 > RS2) Unsigned
JMP 4 if (RS1 >= RS2) Unsigned
JMP C if (RS1 > RS2) Signed
JMP D if (RS1 >= RS2) Signed
### JI Instructions
Compare and then jump (IP = JMP)
JMPI 0 if (True)
JMPI 1 if (RS1 != IMM)
JMPI 2 if (RS1 == IMM)
JMPI 3 if (RS1 > IMM) Unsigned
JMPI 4 if (RS1 >= IMM) Unsigned
JMPI C if (RS1 > IMM) Signed
JMPI D if (RS1 >= IMM) Signed
### Jump Aliases
JEQ
JLT
JGT
JLE
JGE
JLTU
JGTU
JLEU
JGEU
### Control Instructions
NOP Do nothing -> opcode = ZERO
HLT Spinlock the CPU*
PUSHR RS SP+=1 ;*SP = RS
POPR RS RS = *SP ;SP-=1
PUSHI IMM SP+=1 ;*SP = IMM
INVP IMM Invalidate entry in TLB*
JMP IMM Jump to address IMM
CALL LABEL CS0=IP; IP=LABEL
INT IMM CS0=IP; CS1=SP; CS2=FLG; IP=IDT[IMM]*
SCALL Same as call but is used to make calls to the kernel (fixed IDT address)
IRET IP=CS0; SP=CS1; FLG=CS2*
RET IP = CS0
SIF Set interrupt flag*
CIF Clear interrupt flag*
*Requires processor to be in supervisor mode (FLG[17]=0)
## Interrupt Descriptor Table
This will be in a fixed memory location, this will contain pointers to the interupt
function.
IDT[0] Divide-by-zero exception
IDT[1] Hardware error (NMI)
IDT[2] Overflow
IDT[3] Invalid Opcode
IDT[4] General-protection fault
IDT[5] Page fault
IDT[6] Software interrupt (reserved for OS)
IDT[7-31] RESERVED
IDT[32-255] Platform interrupts (PIC, hard drive, keyboard, etc.)
## Page Directory
The page directory contains 1024 page tables that have 1024 entries that are
4096 bytes wide. Optionally, the page table can be 4MB bytes wide with a setting
in the page table. If this bit is set, there is 1024 entries in the page
directory; otherwise, there are 2^20 entries.
### Page table layout
PT[0] Present
PT[1] R/W
PT[2] User-mode
PT[3] Accessed
PT[4] Dirty
PT[5] PWT
PT[6] Cache-disable
PT[7] Page size (0=4KB 1=4MB)
PT[8-31] Physical address of page
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