/
paramParser.c
236 lines (221 loc) · 6.69 KB
/
paramParser.c
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#include <stdint.h>
#include <stdbool.h>
#include "registerFile.h"
#include "paramParser.h"
#include "memory.h"
paramType_t pTypeA;
paramType_t pTypeB;
paramType_t pTypeC;
paramType_t pTypeD;
uint16_t paramA;
uint16_t paramB;
uint16_t paramC;
uint16_t paramD;
/**
* Parse the parameters following an opcode.
* @param paramCount
* @return True if successful, false if parameters are invalid or incomplete.
*/
bool parseParam(uint8_t paramCount) {
uint16_t pointer = regPC + 1;
uint16_t pointer_imm;
uint16_t pointer_reg;
uint16_t pointer_immPtr;
uint16_t pointer_regPtr;
paramType_t pTypeX;
pIdentity_t idX;
uint8_t i;
for (i = 1; i <= paramCount; i++) {
// Select the right parameter blocks to modify for this iteration of the parsing loop
switch (i) {
case 1:
pTypeX = pTypeA;
idX = A;
break;
case 2:
pTypeX = pTypeB;
idX = B;
break;
case 3:
pTypeX = pTypeC;
idX = C;
break;
case 4:
pTypeX = pTypeD;
idX = D;
break;
}
// Test for immediate values
pointer_imm = test_imm(pTypeX, idX, pointer);
if (pointer_imm) {
pointer = pointer_imm;
break;
}
// Test for registers
pointer_reg = test_reg(pTypeX, idX, pointer);
if (pointer_reg) {
pointer = pointer_reg;
break;
}
// Test for immediate 16-bit addresses
pointer_immPtr = test_immPtr(pTypeX, idX, pointer);
if (pointer_immPtr) {
pointer = pointer_immPtr;
break;
}
// Test for 16-bit pointer registers
pointer_regPtr = test_regPtr(pTypeX, idX, pointer);
if (pointer_regPtr) {
pointer = pointer_regPtr;
break;
}
// No valid parameters found, so fail.
return false;
}
// All parameters found are valid, so update regPC and pass.
regPC = pointer;
return true;
}
/**
* Test for an immediate 8-bit or 16-bit value as a parameter.
* @param pType
* @param pIdentity
* @param pointer
* @return Updated pointer if immediate value found, null otherwise.
*/
uint16_t test_imm(paramType_t pType, pIdentity_t pIdentity, uint16_t pointer) {
if (pType.imm && getMemByte(pointer) == 0b00000000) {
// Test for 8-bit immediate values
if (getMemByte(pointer) == 0b00000000) {
switch (pIdentity) {
case A:
paramA = getMemByte(pointer); break;
case B:
paramB = getMemByte(pointer); break;
case C:
paramC = getMemByte(pointer); break;
case D:
paramD = getMemByte(pointer); break;
}
pointer++;
}
// Test for 16-bit immediate values
else if (getMemByte(pointer) == 0b00000011) {
switch (pIdentity) {
case A:
paramA = getMemWord(pointer); break;
case B:
paramB = getMemWord(pointer); break;
case C:
paramC = getMemWord(pointer); break;
case D:
paramD = getMemWord(pointer); break;
}
pointer += 2;
}
return pointer;
} else return 0;
}
/**
* Test for an immediate 16-bit address as a parameter.
* @param pType
* @param pIdentity
* @param pointer
* @return Updated pointer if immediate value found, null otherwise.
*/
uint16_t test_immPtr(paramType_t pType, pIdentity_t pIdentity, uint16_t pointer) {
if (pType.immPtr && getMemByte(pointer) == 0b00000001) {
pointer++;
switch (pIdentity) {
case A:
paramA = getMemWord(pointer); break;
case B:
paramB = getMemWord(pointer); break;
case C:
paramC = getMemWord(pointer); break;
case D:
paramD = getMemWord(pointer); break;
}
pointer += 2;
return pointer;
} else return 0;
}
/**
* Test for a register as a parameter.
* @param pType
* @param pIdentity
* @param pointer
* @return Updated pointer if register found, null otherwise.
*/
uint16_t test_reg(paramType_t pType, pIdentity_t pIdentity, uint16_t pointer) {
uint8_t regCode = getMemByte(pointer);
if (
pType.reg &&
regCode == 0b00001000 || // a
regCode == 0b00001001 || // b
regCode == 0b00001010 || // c
regCode == 0b00001011 || // d
regCode == 0b00001100 || // e
regCode == 0b00001101 || // f
regCode == 0b00100000 || // ab
regCode == 0b00100001 || // cd
regCode == 0b00100010 || // ef
regCode == 0b01000000 || // s
regCode == 0b01000001 || // ix
regCode == 0b01000010 || // iy
regCode == 0b01000011) { // iz
switch (pIdentity) {
case A:
paramA = regCode; break;
case B:
paramB = regCode; break;
case C:
paramC = regCode; break;
case D:
paramD = regCode; break;
}
pointer++;
return pointer;
} else return 0;
}
/**
* Test for a 16-bit register as a parameter, and treat its contents as a 16-bit address.
* @param pType
* @param pIdentity
* @param pointer
* @return Updated pointer if register found, null otherwise.
*/
uint16_t test_regPtr(paramType_t pType, pIdentity_t pIdentity, uint16_t pointer) {
uint8_t regCode;
uint16_t contents;
if (pType.regPtr && getMemByte(pointer) == 0b00000010) {
pointer++;
regCode = getMemByte(pointer);
switch (regCode) {
case 0b00100000: // ab
contents = regAB.regAB; break;
case 0b00100001: // cd
contents = regCD.regCD; break;
case 0b00100010: // ef
contents = regEF.regEF; break;
case 0b01000001: // ix
contents = regIX.regIX; break;
case 0b01000010: // iy
contents = regIY.regIY; break;
case 0b01000011: // iz
contents = regIZ.regIZ; break;
}
switch (pIdentity) {
case A:
paramA = contents; break;
case B:
paramB = contents; break;
case C:
paramC = contents; break;
case D:
paramD = contents; break;
}
pointer++;
return pointer;
} else return 0;
}