ref: e82ad21704bf4df1806195d30d8fa2bf65f0d812
dir: /src/asm/rpn.c/
/*
* This file is part of RGBDS.
*
* Copyright (c) 1997-2018, Carsten Sorensen and RGBDS contributors.
*
* SPDX-License-Identifier: MIT
*/
/*
* Controls RPN expressions for objectfiles
*/
#include <assert.h>
#include <errno.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include "asm/asm.h"
#include "asm/main.h"
#include "asm/rpn.h"
#include "asm/section.h"
#include "asm/symbol.h"
#include "asm/warning.h"
/* Makes an expression "not known", also setting its error message */
#define makeUnknown(expr_, ...) do { \
struct Expression *_expr = expr_; \
_expr->isKnown = false; \
/* If we had `asprintf` this would be great, but alas. */ \
_expr->reason = malloc(128); /* Use an initial reasonable size */ \
if (!_expr->reason) \
fatalerror("Can't allocate err string: %s", strerror(errno)); \
int size = snprintf(_expr->reason, 128, __VA_ARGS__); \
if (size >= 128) { /* If this wasn't enough, try again */ \
_expr->reason = realloc(_expr->reason, size + 1); \
sprintf(_expr->reason, __VA_ARGS__); \
} \
} while (0)
static uint8_t *reserveSpace(struct Expression *expr, uint32_t size)
{
/* This assumes the RPN length is always less than the capacity */
if (expr->nRPNCapacity - expr->nRPNLength < size) {
/* If there isn't enough room to reserve the space, realloc */
if (!expr->tRPN)
expr->nRPNCapacity = 256; /* Initial size */
else if (expr->nRPNCapacity >= MAXRPNLEN)
/*
* To avoid generating humongous object files, cap the
* size of RPN expressions
*/
fatalerror("RPN expression cannot grow larger than %d bytes",
MAXRPNLEN);
else if (expr->nRPNCapacity > MAXRPNLEN / 2)
expr->nRPNCapacity = MAXRPNLEN;
else
expr->nRPNCapacity *= 2;
expr->tRPN = realloc(expr->tRPN, expr->nRPNCapacity);
if (!expr->tRPN)
fatalerror("Failed to grow RPN expression: %s",
strerror(errno));
}
uint8_t *ptr = expr->tRPN + expr->nRPNLength;
expr->nRPNLength += size;
return ptr;
}
/*
* Init the RPN expression
*/
static void rpn_Init(struct Expression *expr)
{
expr->reason = NULL;
expr->isKnown = true;
expr->isSymbol = false;
expr->tRPN = NULL;
expr->nRPNCapacity = 0;
expr->nRPNLength = 0;
expr->nRPNPatchSize = 0;
}
/*
* Free the RPN expression
*/
void rpn_Free(struct Expression *expr)
{
free(expr->tRPN);
free(expr->reason);
rpn_Init(expr);
}
/*
* Add symbols, constants and operators to expression
*/
void rpn_Number(struct Expression *expr, uint32_t i)
{
rpn_Init(expr);
expr->nVal = i;
}
void rpn_Symbol(struct Expression *expr, char *tzSym)
{
struct sSymbol *sym = sym_FindSymbol(tzSym);
if (sym == pPCSymbol && !pPCSymbol->pSection) {
yyerror("PC has no value outside a section");
rpn_Number(expr, 0);
} else if (!sym || !sym_IsConstant(sym)) {
rpn_Init(expr);
expr->isSymbol = true;
sym_Ref(tzSym);
makeUnknown(expr, strcmp(tzSym, "@")
? "'%s' is not constant at assembly time"
: "PC is not constant at assembly time",
tzSym);
expr->nRPNPatchSize += 5; /* 1-byte opcode + 4-byte symbol ID */
size_t nameLen = strlen(tzSym) + 1; /* Don't forget NUL! */
uint8_t *ptr = reserveSpace(expr, nameLen + 1);
*ptr++ = RPN_SYM;
memcpy(ptr, tzSym, nameLen);
/* RGBLINK assumes PC is at the byte being computed... */
if (sym == pPCSymbol && nPCOffset) {
struct Expression pc = *expr, offset;
rpn_Number(&offset, nPCOffset);
rpn_BinaryOp(RPN_SUB, expr, &pc, &offset);
if (!rpn_isKnown(expr))
expr->isSymbol = true;
}
} else {
rpn_Number(expr, sym_GetConstantValue(tzSym));
}
}
void rpn_BankSelf(struct Expression *expr)
{
rpn_Init(expr);
if (!pCurrentSection) {
yyerror("PC has no bank outside a section");
expr->nVal = 1;
} else if (pCurrentSection->nBank == -1) {
makeUnknown(expr, "Current section's bank is not known");
expr->nRPNPatchSize++;
*reserveSpace(expr, 1) = RPN_BANK_SELF;
} else {
expr->nVal = pCurrentSection->nBank;
}
}
void rpn_BankSymbol(struct Expression *expr, char const *tzSym)
{
struct sSymbol const *sym = sym_FindSymbol(tzSym);
/* The @ symbol is treated differently. */
if (sym == pPCSymbol) {
rpn_BankSelf(expr);
return;
}
rpn_Init(expr);
if (sym && !sym_IsLabel(sym)) {
yyerror("BANK argument must be a label");
} else {
sym_Ref(tzSym);
/* If the symbol didn't exist, `sym_Ref` created it */
struct sSymbol *pSymbol = sym_FindSymbol(tzSym);
if (pSymbol->pSection && pSymbol->pSection->nBank != -1) {
/* Symbol's section is known and bank is fixed */
expr->nVal = pSymbol->pSection->nBank;
} else {
makeUnknown(expr, "\"%s\"'s bank is not known", tzSym);
expr->nRPNPatchSize += 5; /* opcode + 4-byte sect ID */
size_t nameLen = strlen(tzSym) + 1; /* Room for NUL! */
uint8_t *ptr = reserveSpace(expr, nameLen + 1);
*ptr++ = RPN_BANK_SYM;
memcpy(ptr, tzSym, nameLen);
}
}
}
void rpn_BankSection(struct Expression *expr, char const *tzSectionName)
{
rpn_Init(expr);
struct Section *pSection = out_FindSectionByName(tzSectionName);
if (pSection && pSection->nBank != -1) {
expr->nVal = pSection->nBank;
} else {
makeUnknown(expr, "Section \"%s\"'s bank is not known",
tzSectionName);
size_t nameLen = strlen(tzSectionName) + 1; /* Room for NUL! */
uint8_t *ptr = reserveSpace(expr, nameLen + 1);
expr->nRPNPatchSize += nameLen + 1;
*ptr++ = RPN_BANK_SECT;
memcpy(ptr, tzSectionName, nameLen);
}
}
void rpn_CheckHRAM(struct Expression *expr, const struct Expression *src)
{
*expr = *src;
expr->isSymbol = false;
if (!rpn_isKnown(expr)) {
expr->nRPNPatchSize++;
*reserveSpace(expr, 1) = RPN_HRAM;
} else if (expr->nVal >= 0xFF00 && expr->nVal <= 0xFFFF) {
/* That range is valid, but only keep the lower byte */
expr->nVal &= 0xFF;
} else if (expr->nVal < 0 || expr->nVal > 0xFF) {
yyerror("Source address $%x not in $FF00 to $FFFF", expr->nVal);
}
}
void rpn_CheckRST(struct Expression *expr, const struct Expression *src)
{
*expr = *src;
if (rpn_isKnown(expr)) {
/* A valid RST address must be masked with 0x38 */
if (expr->nVal & ~0x38)
yyerror("Invalid address $%x for RST", expr->nVal);
/* The target is in the "0x38" bits, all other bits are set */
expr->nVal |= 0xC7;
} else {
expr->nRPNPatchSize++;
*reserveSpace(expr, 1) = RPN_RST;
}
}
void rpn_LOGNOT(struct Expression *expr, const struct Expression *src)
{
*expr = *src;
expr->isSymbol = false;
if (rpn_isKnown(expr)) {
expr->nVal = !expr->nVal;
} else {
expr->nRPNPatchSize++;
*reserveSpace(expr, 1) = RPN_LOGUNNOT;
}
}
static int32_t shift(int32_t shiftee, int32_t amount)
{
if (amount >= 0) {
// Left shift
if (amount >= 32) {
warning(WARNING_SHIFT_AMOUNT, "Shifting left by large amount %d",
amount);
return 0;
} else {
/*
* Use unsigned to force a bitwise shift
* Casting back is OK because the types implement two's
* complement behavior
*/
return (uint32_t)shiftee << amount;
}
} else {
// Right shift
amount = -amount;
if (amount >= 32) {
warning(WARNING_SHIFT_AMOUNT, "Shifting right by large amount %d",
amount);
return shiftee < 0 ? -1 : 0;
} else if (shiftee >= 0) {
return shiftee >> amount;
} else {
/*
* The C standard leaves shifting right negative values
* undefined, so use a left shift manually sign-extended
*/
return (uint32_t)shiftee >> amount
| -((uint32_t)1 << (32 - amount));
}
}
}
static struct sSymbol const *symbolOf(struct Expression const *expr)
{
if (!rpn_isSymbol(expr))
return NULL;
return sym_FindSymbol((char *)expr->tRPN + 1);
}
static bool isDiffConstant(struct Expression const *src1,
struct Expression const *src2)
{
/* Check if both expressions only refer to a single symbol */
struct sSymbol const *symbol1 = symbolOf(src1);
struct sSymbol const *symbol2 = symbolOf(src2);
if (!symbol1 || !symbol2
|| symbol1->type != SYM_LABEL || symbol2->type != SYM_LABEL)
return false;
return symbol1->pSection == symbol2->pSection;
}
void rpn_BinaryOp(enum RPNCommand op, struct Expression *expr,
const struct Expression *src1, const struct Expression *src2)
{
expr->isSymbol = false;
/* First, check if the expression is known */
expr->isKnown = src1->isKnown && src2->isKnown;
if (expr->isKnown) {
rpn_Init(expr); /* Init the expression to something sane */
/* If both expressions are known, just compute the value */
uint32_t uleft = src1->nVal, uright = src2->nVal;
switch (op) {
case RPN_LOGOR:
expr->nVal = src1->nVal || src2->nVal;
break;
case RPN_LOGAND:
expr->nVal = src1->nVal && src2->nVal;
break;
case RPN_LOGEQ:
expr->nVal = src1->nVal == src2->nVal;
break;
case RPN_LOGGT:
expr->nVal = src1->nVal > src2->nVal;
break;
case RPN_LOGLT:
expr->nVal = src1->nVal < src2->nVal;
break;
case RPN_LOGGE:
expr->nVal = src1->nVal >= src2->nVal;
break;
case RPN_LOGLE:
expr->nVal = src1->nVal <= src2->nVal;
break;
case RPN_LOGNE:
expr->nVal = src1->nVal != src2->nVal;
break;
case RPN_ADD:
expr->nVal = uleft + uright;
break;
case RPN_SUB:
expr->nVal = uleft - uright;
break;
case RPN_XOR:
expr->nVal = src1->nVal ^ src2->nVal;
break;
case RPN_OR:
expr->nVal = src1->nVal | src2->nVal;
break;
case RPN_AND:
expr->nVal = src1->nVal & src2->nVal;
break;
case RPN_SHL:
if (src2->nVal < 0)
warning(WARNING_SHIFT_AMOUNT, "Shifting left by negative amount %d",
src2->nVal);
expr->nVal = shift(src1->nVal, src2->nVal);
break;
case RPN_SHR:
if (src1->nVal < 0)
warning(WARNING_SHIFT, "Shifting negative value %d",
src1->nVal);
if (src2->nVal < 0)
warning(WARNING_SHIFT_AMOUNT, "Shifting right by negative amount %d",
src2->nVal);
expr->nVal = shift(src1->nVal, -src2->nVal);
break;
case RPN_MUL:
expr->nVal = uleft * uright;
break;
case RPN_DIV:
if (src2->nVal == 0)
fatalerror("Division by zero");
if (src1->nVal == INT32_MIN
&& src2->nVal == -1) {
warning(WARNING_DIV, "Division of min value by -1");
expr->nVal = INT32_MIN;
} else {
expr->nVal = src1->nVal / src2->nVal;
}
break;
case RPN_MOD:
if (src2->nVal == 0)
fatalerror("Division by zero");
if (src1->nVal == INT32_MIN && src2->nVal == -1)
expr->nVal = 0;
else
expr->nVal = src1->nVal % src2->nVal;
break;
case RPN_UNSUB:
case RPN_UNNOT:
case RPN_LOGUNNOT:
case RPN_BANK_SYM:
case RPN_BANK_SECT:
case RPN_BANK_SELF:
case RPN_HRAM:
case RPN_RST:
case RPN_CONST:
case RPN_SYM:
fatalerror("%d is no binary operator", op);
}
} else if (op == RPN_SUB && isDiffConstant(src1, src2)) {
struct sSymbol const *symbol1 = symbolOf(src1);
struct sSymbol const *symbol2 = symbolOf(src2);
expr->nVal = sym_GetValue(symbol1) - sym_GetValue(symbol2);
expr->isKnown = true;
} else {
/* If it's not known, start computing the RPN expression */
/* Convert the left-hand expression if it's constant */
if (src1->isKnown) {
uint32_t lval = src1->nVal;
uint8_t bytes[] = {RPN_CONST, lval, lval >> 8,
lval >> 16, lval >> 24};
expr->nRPNPatchSize = sizeof(bytes);
expr->tRPN = NULL;
expr->nRPNCapacity = 0;
expr->nRPNLength = 0;
memcpy(reserveSpace(expr, sizeof(bytes)), bytes,
sizeof(bytes));
/* Use the other expression's un-const reason */
expr->reason = src2->reason;
free(src1->reason);
} else {
/* Otherwise just reuse its RPN buffer */
expr->nRPNPatchSize = src1->nRPNPatchSize;
expr->tRPN = src1->tRPN;
expr->nRPNCapacity = src1->nRPNCapacity;
expr->nRPNLength = src1->nRPNLength;
expr->reason = src1->reason;
free(src2->reason);
}
/* Now, merge the right expression into the left one */
uint8_t *ptr = src2->tRPN; /* Pointer to the right RPN */
uint32_t len = src2->nRPNLength; /* Size of the right RPN */
uint32_t patchSize = src2->nRPNPatchSize;
/* If the right expression is constant, merge a shim instead */
uint32_t rval = src2->nVal;
uint8_t bytes[] = {RPN_CONST, rval, rval >> 8, rval >> 16,
rval >> 24};
if (src2->isKnown) {
ptr = bytes;
len = sizeof(bytes);
patchSize = sizeof(bytes);
}
/* Copy the right RPN and append the operator */
uint8_t *buf = reserveSpace(expr, len + 1);
memcpy(buf, ptr, len);
buf[len] = op;
free(src2->tRPN); /* If there was none, this is `free(NULL)` */
expr->nRPNPatchSize += patchSize + 1;
}
}
void rpn_HIGH(struct Expression *expr, const struct Expression *src)
{
*expr = *src;
expr->isSymbol = false;
if (rpn_isKnown(expr)) {
expr->nVal = (uint32_t)expr->nVal >> 8 & 0xFF;
} else {
uint8_t bytes[] = {RPN_CONST, 8, 0, 0, 0, RPN_SHR,
RPN_CONST, 0xFF, 0, 0, 0, RPN_AND};
expr->nRPNPatchSize += sizeof(bytes);
memcpy(reserveSpace(expr, sizeof(bytes)), bytes, sizeof(bytes));
}
}
void rpn_LOW(struct Expression *expr, const struct Expression *src)
{
*expr = *src;
expr->isSymbol = false;
if (rpn_isKnown(expr)) {
expr->nVal = expr->nVal & 0xFF;
} else {
uint8_t bytes[] = {RPN_CONST, 0xFF, 0, 0, 0, RPN_AND};
expr->nRPNPatchSize += sizeof(bytes);
memcpy(reserveSpace(expr, sizeof(bytes)), bytes, sizeof(bytes));
}
}
void rpn_ISCONST(struct Expression *expr, const struct Expression *src)
{
rpn_Init(expr);
expr->nVal = rpn_isKnown(src);
expr->isKnown = true;
expr->isSymbol = false;
}
void rpn_UNNEG(struct Expression *expr, const struct Expression *src)
{
*expr = *src;
expr->isSymbol = false;
if (rpn_isKnown(expr)) {
expr->nVal = -(uint32_t)expr->nVal;
} else {
expr->nRPNPatchSize++;
*reserveSpace(expr, 1) = RPN_UNSUB;
}
}
void rpn_UNNOT(struct Expression *expr, const struct Expression *src)
{
*expr = *src;
expr->isSymbol = false;
if (rpn_isKnown(expr)) {
expr->nVal = ~expr->nVal;
} else {
expr->nRPNPatchSize++;
*reserveSpace(expr, 1) = RPN_UNNOT;
}
}