Add overlay file option to rgblink (-O)

This option takes a file and places fixed sections on top of it.
Should prove useful for patches and partial disassemblies.

include/link/mylink.h

@@ -10,6 +10,7 @@
 extern SLONG options;
 #define OPT_SMALL	0x01
 #define OPT_SMART_C_LINK	0x02
+#define OPT_OVERLAY	0x04
 
 enum eRpnData {
 	RPN_ADD = 0,

include/link/output.h

@@ -2,6 +2,7 @@
 #define	RGBDS_LINK_OUTPUT_H
 
 void out_Setname(char *tzOutputfile);
+void out_SetOverlayname(char *tzOverlayfile);
 void Output(void);
 
 #endif

src/link/assign.c

@@ -713,6 +713,10 @@ AssignSections(void)
 		    && pSection->Type == SECT_ROMX
 		    && pSection->nOrg == -1 && pSection->nBank != -1) {
 			/* User wants to have a say... and he's pissed */
+			if (options & OPT_OVERLAY) {
+			    errx(1, "All ROM sections must be fixed when using overlay");
+            }
+			
 			if (pSection->nBank >= 1 && pSection->nBank <= 511) {
 				if ((pSection->nOrg =
 					area_Alloc(&BankFree[pSection->nBank],
@@ -789,6 +793,9 @@ AssignSections(void)
 		    && pSection->nOrg != -1 && pSection->nBank == -1) {
 			/* User wants to have a say... and he's back with a
 			 * vengeance */
+			if (options & OPT_OVERLAY) {
+			    errx(1, "All ROM sections must be fixed when using overlay");
+            }
 			if ((pSection->nBank =
 				area_AllocAbsROMXAnyBank(pSection->nOrg,
 				    pSection->nByteSize)) ==
@@ -875,6 +882,9 @@ AssignSections(void)
 			case SECT_WRAMX:
 				break;
 			case SECT_ROM0:
+			    if (options & OPT_OVERLAY) {
+			        errx(1, "All ROM sections must be fixed when using overlay");
+                }
 				if ((pSection->nOrg =
 					area_Alloc(&BankFree[BANK_ROM0],
 					    pSection->nByteSize)) == -1) {
@@ -884,6 +894,9 @@ AssignSections(void)
 				pSection->oAssigned = 1;
 				break;
 			case SECT_ROMX:
+			    if (options & OPT_OVERLAY) {
+			        errx(1, "All ROM sections must be fixed when using overlay");
+                }
 				break;
 			default:
 				errx(1, "(INTERNAL) Unknown section type!");

src/link/main.c

@@ -35,8 +35,8 @@ static void
 usage(void)
 {
 	printf(
-"usage: rgblink [-t] [-m mapfile] [-n symfile] [-o outfile] [-p pad_value]\n"
-"               [-s symbol] file [...]\n");
+"usage: rgblink [-t] [-m mapfile] [-n symfile] [-O overlay] [-o outfile] \n"
+"               [-p pad_value] [-s symbol] file [...]\n");
 	exit(1);
 }
 
@@ -56,7 +56,7 @@ main(int argc, char *argv[])
 
 	progname = argv[0];
 
-	while ((ch = getopt(argc, argv, "m:n:o:p:s:t")) != -1) {
+	while ((ch = getopt(argc, argv, "m:n:o:O:p:s:t")) != -1) {
 		switch (ch) {
 		case 'm':
 			SetMapfileName(optarg);
@@ -67,6 +67,10 @@ main(int argc, char *argv[])
 		case 'o':
 			out_Setname(optarg);
 			break;
+		case 'O':
+			out_SetOverlayname(optarg);
+			options |= OPT_OVERLAY;
+			break;
 		case 'p':
 			fillchar = strtoul(optarg, &ep, 0);
 			if (optarg[0] == '\0' || *ep != '\0') {

src/link/output.c

@@ -8,9 +8,12 @@
 #include "link/assign.h"
 
 char *tzOutname;
+char *tzOverlayname = NULL;
+
+SLONG MaxOverlayBank;
 
 void 
-writehome(FILE * f)
+writehome(FILE * f, FILE * f_overlay)
 {
 	struct sSection *pSect;
 	UBYTE *mem;
@@ -18,15 +21,20 @@ writehome(FILE * f)
 	mem = malloc(MaxAvail[BANK_ROM0]);
 	if (!mem)
 		return;
-
-	memset(mem, fillchar, MaxAvail[BANK_ROM0]);
+	
+	if (f_overlay != NULL) {
+		fseek(f_overlay, 0L, SEEK_SET);
+		fread(mem, 1, MaxAvail[BANK_ROM0], f_overlay);
+	} else {
+		memset(mem, fillchar, MaxAvail[BANK_ROM0]);
+	}
 	MapfileInitBank(0);
 
 	pSect = pSections;
 	while (pSect) {
 		if (pSect->Type == SECT_ROM0) {
 			memcpy(mem + pSect->nOrg, pSect->pData,
-			    pSect->nByteSize);
+				pSect->nByteSize);
 			MapfileWriteSection(pSect);
 		}
 		pSect = pSect->pNext;
@@ -39,7 +47,7 @@ writehome(FILE * f)
 }
 
 void 
-writebank(FILE * f, SLONG bank)
+writebank(FILE * f, FILE * f_overlay, SLONG bank)
 {
 	struct sSection *pSect;
 	UBYTE *mem;
@@ -48,14 +56,19 @@ writebank(FILE * f, SLONG bank)
 	if (!mem)
 		return;
 
-	memset(mem, fillchar, MaxAvail[bank]);
+	if (f_overlay != NULL && bank <= MaxOverlayBank) {
+		fseek(f_overlay, bank*0x4000, SEEK_SET);
+		fread(mem, 1, MaxAvail[bank], f_overlay);
+	} else {
+		memset(mem, fillchar, MaxAvail[bank]);
+	}
 	MapfileInitBank(bank);
 
 	pSect = pSections;
 	while (pSect) {
 		if (pSect->Type == SECT_ROMX && pSect->nBank == bank) {
 			memcpy(mem + pSect->nOrg - 0x4000, pSect->pData,
-			    pSect->nByteSize);
+				pSect->nByteSize);
 			MapfileWriteSection(pSect);
 		}
 		pSect = pSect->pNext;
@@ -73,18 +86,48 @@ out_Setname(char *tzOutputfile)
 	tzOutname = tzOutputfile;
 }
 
+void 
+out_SetOverlayname(char *tzOverlayfile)
+{
+	tzOverlayname = tzOverlayfile;
+}
+
+
 void 
 Output(void)
 {
 	SLONG i;
 	FILE *f;
+	FILE *f_overlay = NULL;
+	
 
 	if ((f = fopen(tzOutname, "wb"))) {
-		writehome(f);
+		if (tzOverlayname) {
+			f_overlay = fopen(tzOverlayname, "rb");
+			fseek(f_overlay, 0, SEEK_END);
+			if (ftell(f_overlay) % 0x4000 != 0) {
+			    fprintf(stderr, "Overlay file must be aligned to 0x4000 bytes");
+			    exit(1);
+			}
+			MaxOverlayBank = (ftell(f_overlay) / 0x4000) - 1;
+			if (MaxOverlayBank < 1) {
+			    fprintf(stderr, "Overlay file be at least 0x8000 bytes");
+			    exit(1);
+			}
+			if (MaxOverlayBank > MaxBankUsed) {
+				MaxBankUsed = MaxOverlayBank;
+			}
+		}
+		
+		writehome(f, f_overlay);
 		for (i = 1; i <= MaxBankUsed; i += 1)
-			writebank(f, i);
+			writebank(f, f_overlay, i);
 
 		fclose(f);
+		
+		if (tzOverlayname) {
+			fclose(f_overlay);
+		}
 	}
 	for (i = BANK_WRAM0; i < MAXBANKS; i++) {
 		struct sSection *pSect;