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Fix `@`
The symbol's evaluation by the assembler and linker was very inconsistent

--- a/include/asm/rpn.h

+++ b/include/asm/rpn.h

@@ -23,6 +23,9 @@

 	uint32_t isReloc;

 };

+/* FIXME: Should be defined in `asmy.h`, but impossible with POSIX Yacc */

+extern int32_t nPCOffset;

+

 uint32_t rpn_isReloc(const struct Expression *expr);

 void rpn_Symbol(struct Expression *expr, char *tzSym);

 void rpn_Number(struct Expression *expr, uint32_t i);

--- a/src/asm/asmy.y

+++ b/src/asm/asmy.y

@@ -1206,37 +1206,7 @@

 relocconst	: T_ID

 		{

-			/*

-			 * The value of @ needs to be evaluated by the linker,

-			 * it can only be calculated by the assembler in very

-			 * few cases (when the base address of a section is

-			 * known).

-			 *

-			 * '@' is a bit special in that it means different

-			 * things depending on when it is used:

-			 *

-			 * - JR/LD/ADD/etc: It refers to the first byte of the

-			 *   instruction (1 byte offset relative to the value

-			 *   stored in the ROM).

-			 * - DB/DW/DL: It refers to the address of the value

-			 *   that is being saved (0 byte offset relative to the

-			 *   value stored in the ROM.

-			 *

-			 * This offset must be added whenever '@' is added to a

-			 * RPN expression so that the linker can calculate the

-			 * correct result of any expression that uses '@'.

-			 */

-			if ((strcmp($1, "@") == 0) && (nPCOffset != 0)) {

-				struct Expression sTemp, sOffset;

-

-				rpn_Symbol(&sTemp, $1);

-

-				rpn_Number(&sOffset, nPCOffset);

-

-				rpn_SUB(&$$, &sTemp, &sOffset);

-			} else {

-				rpn_Symbol(&$$, $1);

-			}

+			rpn_Symbol(&$$, $1);

 		}

 		| T_NUMBER

 		{

--- a/src/asm/rpn.c

+++ b/src/asm/rpn.c

@@ -154,6 +154,14 @@

 			pushbyte(expr, *tzSym++);

 		pushbyte(expr, 0);

 		expr->nRPNPatchSize += 5;

+

+		/* RGBLINK assumes PC is at the byte being computed... */

+		if (sym == pPCSymbol && nPCOffset) {

+			struct Expression pc = *expr, offset;

+

+			rpn_Number(&offset, nPCOffset);

+			rpn_SUB(expr, &pc, &offset);

+		}

 	} else {

 		rpn_Number(expr, sym_GetConstantValue(tzSym));

 	}