mirror of https://github.com/cc65/cc65.git
151 lines
5.1 KiB
C
151 lines
5.1 KiB
C
/*****************************************************************************/
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/* */
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/* easw16.c */
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/* */
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/* SWEET16 effective address parsing for the ca65 macroassembler */
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/* */
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/* */
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/* */
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/* (C) 2004-2011, Ullrich von Bassewitz */
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/* Roemerstrasse 52 */
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/* D-70794 Filderstadt */
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/* EMail: uz@cc65.org */
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/* */
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/* */
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/* This software is provided 'as-is', without any expressed or implied */
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/* warranty. In no event will the authors be held liable for any damages */
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/* arising from the use of this software. */
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/* */
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/* Permission is granted to anyone to use this software for any purpose, */
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/* including commercial applications, and to alter it and redistribute it */
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/* freely, subject to the following restrictions: */
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/* */
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/* 1. The origin of this software must not be misrepresented; you must not */
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/* claim that you wrote the original software. If you use this software */
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/* in a product, an acknowledgment in the product documentation would be */
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/* appreciated but is not required. */
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/* 2. Altered source versions must be plainly marked as such, and must not */
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/* be misrepresented as being the original software. */
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/* 3. This notice may not be removed or altered from any source */
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/* distribution. */
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/* */
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/*****************************************************************************/
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/* ca65 */
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#include "ea.h"
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#include "ea65.h"
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#include "error.h"
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#include "expr.h"
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#include "instr.h"
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#include "nexttok.h"
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/*****************************************************************************/
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/* Code */
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/*****************************************************************************/
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static long RegNum ()
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/* Try to read a register number specified not as a register (Rx) but as a
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** numeric value between 0 and 15. Return the register number or -1 on
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** failure.
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*/
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{
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long Val;
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ExprNode* Expr = Expression ();
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if (!IsConstExpr (Expr, &Val) || Val < 0 || Val > 15) {
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/* Invalid register */
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Val = -1L;
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}
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/* Free the expression and return the register number */
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FreeExpr (Expr);
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return Val;
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}
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void GetSweet16EA (EffAddr* A)
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/* Parse an effective address, return the result in A */
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{
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long Reg;
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/* Clear the output struct */
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A->AddrModeSet = 0;
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A->Expr = 0;
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A->Reg = 0;
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/* Parse the effective address */
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if (TokIsSep (CurTok.Tok)) {
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A->AddrModeSet = AMSW16_IMP;
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} else if (CurTok.Tok == TOK_AT) {
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/* @reg or @regnumber */
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A->AddrModeSet = AMSW16_IND;
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NextTok ();
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if (CurTok.Tok == TOK_REG) {
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A->Reg = (unsigned) CurTok.IVal;
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NextTok ();
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} else if ((Reg = RegNum ()) >= 0) {
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/* Register number */
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A->Reg = (unsigned) Reg;
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} else {
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ErrorSkip ("Register or register number expected");
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A->Reg = 0;
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}
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} else if (CurTok.Tok == TOK_REG) {
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A->Reg = (unsigned) CurTok.IVal;
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NextTok ();
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if (CurTok.Tok == TOK_COMMA) {
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/* Rx, constant */
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NextTok ();
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A->Expr = Expression ();
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A->AddrModeSet = AMSW16_IMM;
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} else {
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A->AddrModeSet = AMSW16_REG;
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}
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} else {
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/* OPC ea or: OPC regnum, constant */
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A->Expr = Expression ();
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A->AddrModeSet = AMSW16_BRA;
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/* If the value is a constant between 0 and 15, it may also be a
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** register number.
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*/
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if (IsConstExpr (A->Expr, &Reg) && Reg >= 0 && Reg <= 15) {
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FreeExpr (A->Expr);
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A->Reg = (unsigned) Reg;
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/* If a comma follows, it is: OPC Rx, constant */
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if (CurTok.Tok == TOK_COMMA) {
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NextTok ();
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A->Expr = Expression ();
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A->AddrModeSet = AMSW16_IMM;
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} else {
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A->Expr = 0;
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A->AddrModeSet |= AMSW16_REG;
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}
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}
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}
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}
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