ref: 665412c07352379651334fc59cb75a6661242a35
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; } }