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5e: fix special bitshift and rotations

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This commit is contained in:
cinap_lenrek 2017-05-01 20:22:23 +02:00
parent 359955ee4b
commit d63cc467d8
1 changed files with 70 additions and 35 deletions
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105
sys/src/cmd/5e/arm.c
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@ -35,29 +35,60 @@ evenaddr(u32int addr, u32int mask)
}
static u32int
doshift(u32int instr)
doshift(u32int instr, u8int *carry)
{
ulong amount, val;
if((instr & (1<<4)) && (instr & (1<<7)))
invalid(instr);
if(instr & (1<<4))
amount = P->R[(instr >> 8) & 15];
else
amount = (instr >> 7) & 31;
val = P->R[instr & 15];
switch((instr >> 5) & 3) {
case 0:
return val << amount;
case 1:
return val >> amount;
case 2:
return ((long) val) >> amount;
case 3:
return (val >> amount) | (val << (32 - amount));
if(instr & (1<<4)) {
if(instr & (1<<7))
invalid(instr);
amount = P->R[(instr >> 8) & 15] & 0xFF;
if(amount == 0)
return val;
} else {
amount = (instr >> 7) & 31;
if(amount == 0 && (instr & (3<<5)) != 0)
amount = 32;
}
switch((instr >> 5) & 3) {
default:
if(amount == 0)
return val;
if(amount < 32) {
*carry = (val >> (32 - amount)) & 1;
return val << amount;
}
*carry = val & 1;
return 0;
case 1:
if(amount < 32){
*carry = (val >> (amount - 1)) & 1;
return val >> amount;
}
*carry = val >> 31;
return 0;
case 2:
if(amount < 32){
*carry = (val >> (amount - 1)) & 1;
return ((long) val) >> amount;
}
if((long)val < 0){
*carry = 1;
return -1;
}
*carry = 0;
return 0;
case 3:
amount &= 31;
if(amount){
*carry = (val >> (amount - 1)) & 1;
return (val >> amount) | (val << (32 - amount));
}
amount = *carry & 1;
*carry = val & 1;
return (val>>1) | (amount<<31);
}
return 0;
}
static void
@ -70,9 +101,10 @@ single(u32int instr)
Segment *seg;
if(instr & fI) {
u8int carry = 0;
if(instr & (1<<4))
invalid(instr);
offset = doshift(instr);
offset = doshift(instr, &carry);
} else
offset = instr & ((1<<12) - 1);
if(!(instr & fU))
@ -165,12 +197,14 @@ add(u32int a, u32int b, u8int type, u8int *carry, u8int *overflow)
res2 = (u64int)a - b + *carry - 1;
res1 = res2;
if(((a ^ b) & (1<<31)) && !((b ^ res1) & (1<<31))) *overflow = 1;
else *overflow = 0;
if(res2 & 0x100000000LL) *carry = 0;
else *carry = 1;
} else {
res2 = (u64int)a + b + *carry;
res1 = res2;
if(!((a ^ b) & (1<<31)) && ((b ^ res1) & (1<<31))) *overflow = 1;
else *overflow = 0;
if(res2 & 0x100000000LL) *carry = 1;
else *carry = 0;
}
@ -192,30 +226,31 @@ alu(u32int instr)
}
if(Rd == P->R + 15 && (instr & fS))
invalid(instr);
carry = (P->CPSR & flC) != 0;
overflow = (P->CPSR & flV) != 0;
if(instr & fI) {
operand = instr & 0xFF;
shift = ((instr >> 8) & 15) << 1;
operand = (operand >> shift) | (operand << (32 - shift));
if(shift){
operand = (operand >> shift) | (operand << (32 - shift));
carry = operand >> 31;
}
} else
operand = doshift(instr);
operand = doshift(instr, &carry);
op = (instr >> 21) & 15;
carry = 0;
if(op >= 8 && op <= 11 && !(instr & fS))
sysfatal("no PSR transfers plz");
if(op >= 5 && op < 8) {
if(P->CPSR & flC)
carry = 1;
} else {
if(op != 4 && op != 5 && op != 11)
carry = 1;
}
overflow = 0;
if(op >= 5 && op < 8)
carry = (P->CPSR & flC) != 0;
switch(op) {
case 0: case 8: result = Rn & operand; break;
case 1: case 9: result = Rn ^ operand; break;
case 2: case 6: case 10: result = add(Rn, operand, 1, &carry, &overflow); break;
case 3: case 7: result = add(operand, Rn, 1, &carry, &overflow); break;
case 4: case 5: case 11: result = add(operand, Rn, 0, &carry, &overflow); break;
case 2: case 10: carry = 1; case 6: result = add(Rn, operand, 1, &carry, &overflow); break;
case 3: carry = 1; case 7: result = add(operand, Rn, 1, &carry, &overflow); break;
case 4: case 11: carry = 0; case 5: result = add(operand, Rn, 0, &carry, &overflow); break;
case 12: result = Rn | operand; break;
case 13: result = operand; break;
case 14: result = Rn & ~operand; break;
@ -228,7 +263,7 @@ alu(u32int instr)
P->CPSR |= flZ;
if(result & (1<<31))
P->CPSR |= flN;
if(carry && op > 1 && op < 12)
if(carry)
P->CPSR |= flC;
if(overflow)
P->CPSR |= flV;