Better parsing of rvvi.

This commit is contained in:
Ross Thompson 2024-06-11 14:36:34 -07:00
parent 563980443a
commit 3d9f796f21

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@ -75,22 +75,15 @@ typedef struct {
uint8_t GPREn : 1;
uint8_t FPREn : 1;
uint16_t CSRCount : 12;
} RequiredRVVI_t; // total size is 241 bits or 30.25 bytes
} RequiredRVVI_t; // total size is 241 bits or 30.125 bytes
typedef struct {
uint8_t fill : 1; // *** depends on the size of the RequiredRVVI_t
uint8_t RegAddress : 5;
uint64_t RegValue;
} FirstReg_t;
typedef struct {
uint8_t fill : 6; // *** depends on the size of the RequiredRVVI_t and FirstReg_t
uint8_t RegAddress : 5;
uint64_t RegValue;
} SecondReg_t;
} Reg_t;
void DecodeRVVI(uint8_t *payload, uint64_t * PC, uint32_t *insn);
void BitShiftArray(uint8_t *dst, uint8_t *src, uint8_t ShiftAmount, int Length);
int main(int argc, char **argv){
@ -164,14 +157,78 @@ int main(int argc, char **argv){
void DecodeRVVI(uint8_t *payload, uint64_t * PC, uint32_t *insn){
// you know this actually easiser in assembly. :(
uint8_t buf2[BUF_SIZ], buf3[BUF_SIZ];
//int PayloadSize = sizeof(RequiredRVVI_t) - 1;
int PayloadSize = 30;
int Buf2Size = BUF_SIZ - PayloadSize;
RequiredRVVI_t *RequiredFields = (RequiredRVVI_t *) payload;
FirstReg_t FirstReg;
SecondReg_t SecondReg;
*PC = RequiredFields->PC;
*insn = RequiredFields->insn;
printf("PC = %lx, insn = %x\n", *PC, *insn);
uint8_t *CurrentBytePointer = payload + PayloadSize;
Reg_t *FirstReg;
Reg_t SecondReg;
uint64_t Mcycle, Minstret;
// unforunately the struct appoarch does not work?!?
//*PC = RequiredFields->PC;
*PC = * (uint64_t *) payload;
//*insn = RequiredFields->insn;
payload += 8;
*insn = * (uint32_t *) payload;
// Mcycle = RequiredFields->Mcycle;
payload += 4;
Mcycle = * (uint64_t *) payload;
payload += 8;
Minstret = * (uint64_t *) payload;
//Minstret = RequiredFields->Minstret;
payload += 8;
// the next 4 bytes contain CSRCount (12), FPRWen(1), GPRWen(1), PrivilegeMode(2), Trap(1)
uint32_t RequiredFlags;
RequiredFlags = * (uint32_t *) payload;
uint8_t Trap, PrivilegeMode, GPRWen, FPRWen;
uint16_t CSRCount;
Trap = RequiredFlags & 0x1;
PrivilegeMode = (RequiredFlags >> 1) & 0x3;
GPRWen = (RequiredFlags >> 3) & 0x1;
FPRWen = (RequiredFlags >> 4) & 0x1;
CSRCount = (RequiredFlags >> 5) & 0xFFF;
int bits;
printf("PC = %lx, insn = %x, Mcycle = %lx, Minstret = %lx, Trap = %hhx, PrivilegeMode = %hhx, GPRWen = %hhx, FPRWen = %hhx, CSRCount == %hx\n", *PC, *insn, Mcycle, Minstret, Trap, PrivilegeMode, GPRWen, FPRWen, CSRCount);
if(RequiredFields->GPREn){
FirstReg = *(FirstReg_t *) (payload + sizeof(RequiredRVVI_t) - 1);
printf("Wrote a reg\n");
BitShiftArray(buf2, CurrentBytePointer, 1, Buf2Size);
FirstReg = (Reg_t *) buf2;
printf("Wrote reg %d = %lx\n", FirstReg->RegAddress, FirstReg->RegValue);
}
printf("!!!!!\n\n");
}
void BitShiftArray(uint8_t *dst, uint8_t *src, uint8_t ShiftAmount, int Length){
// always shift right by ShiftAmount (0 to 7 bit positions).
// *** this implemenation is very inefficient. improve later.
if(ShiftAmount < 0 || ShiftAmount > 7) return;
/* Read the first source byte
Read the second source byte
Right Shift byte 1 by ShiftAmount
Right Rotate byte 2 by ShiftAmount
Mask byte 2 by ~(2^ShiftAmount -1)
OR together the two bytes to form the final next byte
repeat this for each byte
On the last byte we don't do the last steps
*/
int Index;
for(Index = 0; Index < Length - 1; Index++){
uint8_t byte1 = src[Index];
uint8_t byte2 = src[Index+1];
byte1 = byte1 >> ShiftAmount;
uint8_t byte2rot = byte2 >> ShiftAmount | byte2 << (unsigned) (8 - ShiftAmount);
byte2rot = byte2rot & ~(2^ShiftAmount - 1);
uint8_t byte1final = byte2rot | byte1;
dst[Index] = byte1final;
}
// fence post
// For last one there is only one source byte
uint8_t byte1 = src[Length-1];
byte1 = byte1 >> ShiftAmount;
dst[Length-1] = byte1;
}