eeeck/tyvm
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minor improvements on ldi

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This commit is contained in:
Erick
2022-02-04 01:41:16 +01:00
parent b5e5fa8976
commit f89c89a7f3
1 changed files with 11 additions and 10 deletions
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tyvm.c
+11 -10
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@@ -51,13 +51,13 @@ uint16_t memory[UINT16_MAX];
uint16_t reg[RG_COUNT];
/* Creating instruction set opcodes */
enum opcodes { // [description, opcode value]
enum opcodes { // [name, value]
OP_BR = 0, // branch,
OP_ADD, // add, 0001
OP_LD, // load,
OP_LD, // load, 0010
OP_ST, // store,
OP_JSR, // jump register,
OP_AND, // bitwise and,
OP_AND, // bitwise and, 0101
OP_LDR, // load register,
OP_STR, // store register,
OP_RTI, // unused opcode
@@ -120,7 +120,7 @@ int main(int argc, const char* argv[]) {
switch (op) {
case OP_BR:
{BR};
//{BR};
break;
case OP_ADD:
uint16_t dr = (instr >> 9) & 0x7; // destination register
@@ -141,7 +141,10 @@ int main(int argc, const char* argv[]) {
break;
case OP_LD:
//{LD};
break;
case OP_ST:
//{ST}
@@ -177,12 +180,10 @@ int main(int argc, const char* argv[]) {
//{NOT};
break;
case OP_LDI:
uint16_t mdr; // memory data register
uint16_t dr = (instr >> 9) & 0x7;
uint16_t PCoffset9 = sign_extend(instr & 0x1FF, 9); // 9-bit value that indicates where to load the address when added to RG_PC
reg[mdr] = mem_read(PCoffset9 + reg[RG_PC]++);
reg[dr] = mem_read(reg[mdr]);
reg[dr] = mem_read(mem_read(PCoffset9 + reg[RG_PC]++));
update_flags(dr);
@@ -199,8 +200,8 @@ int main(int argc, const char* argv[]) {
case OP_TRAP:
//{TRAP};
break;
case OP_RES:
case OP_RTI:
case OP_RES: // reserved
case OP_RTI: // unused
default:
//{BAD_OPCODE}
break;