Ok, last changes tonight for real

Makefile

@@ -21,15 +21,6 @@ binaries:		## Build all small binaries
 	docker build --build-arg TARGET=readio.bin -o . --target=export .
 	docker build --build-arg TARGET=writeio.bin -o . --target=export .
 
-.PHONY: polos
-polos:			## Build polOS components
-	docker build --build-arg TARGET=fat12boot.bin -o . --target=export .
-	docker build --build-arg TARGET=polio.com -o . --target=export .
-	docker build --build-arg TARGET=polmon.com -o . --target=export .
-	docker build --build-arg TARGET=mushroom.com -o . --target=export .
-	docker build --build-arg TARGET=hello.com -o . --target=export .
-	docker build --build-arg TARGET=ftpget.com -o . --target=export .
-
 .PHONY: floppy
 floppy:			## Make a bootable floppy image
 	docker build --build-arg TARGET=polos.img -o . --target=export .

src/Makefile

@@ -1,27 +1,22 @@
-%.bin: %.asm
-	nasm $< -o $@
-
-crc16.s: crc16.c
-	ia16-elf-gcc -S -Os -o crc16.s crc16.c
-
-crc16.bin: crc16.s
-	ia16-elf-gcc -o crc16.bin -Os -nostdlib crc16.s
-
 CC = ia16-elf-gcc
 CXX = ia16-elf-gcc
 LD = ia16-elf-gcc
+OBJCOPY = ia16-elf-objcopy
 CXXFLAGS = -mregparmcall -ffunction-sections -Os -flto
 CFLAGS = -mregparmcall -ffunction-sections -Os -flto
 LDFLAGS = -mregparmcall -Wl,--gc-sections -Os -nostdlib -flto
 
+%.bin: %.asm
+	nasm $< -o $@
+
 %.elf:
 	$(LD) $(LDFLAGS) $(CPPFLAGS) -o $@ $^
 
 %.com: %.elf
-	ia16-elf-objcopy -O binary $< $@
+	$(OBJCOPY) -O binary $< $@
 
 fat12boot.bin:
-	ia16-elf-objcopy -O binary $< $@
+	$(OBJCOPY) -O binary $< $@
 
 fat12boot.elf: fat12boot.o fat12.o bootsect.S
 fat12boot.elf: LDFLAGS += -T bootsect.ld
@@ -39,12 +34,13 @@ polio.elf: polio-main.o polio.s fat12.o paracomm.o stdlib.o
 paracli.elf: LDFLAGS += -T doscom.ld
 paracli.elf: paracli.s paracomm.o
 
-dos-programs = mushroom.com hello.com ftpget.com
+dos-programs = mushroom.com hello.com ftpget.com crc16.com
 $(dos-programs:.com=.elf): LDFLAGS += -T doscom.ld
 
 mushroom.elf: mushroom.s
 hello.elf: hello.o stdlib.o crt0.s
 ftpget.elf: ftpget.o stdlib.o crt0.s
+crc16.elf: crc16.o stdlib.o crt0.s
 
 polos.img: fat12boot.bin polmon.com polio.com $(dos-programs)
 	dd if=/dev/zero of=$@ bs=512 count=720

src/crc16.c

@@ -1,13 +1,13 @@
 #include <stdint.h>
 
-#define kDataAddr ((uint8_t*)0x0000)
+#include "polos.h"
 
-uint16_t crc16(int data_len) {
+#define kDefaultSegment 0
-    const uint8_t* data = kDataAddr;
 
+uint16_t crc16(uint16_t data, const uint16_t seg, int data_len) {
     uint16_t crc = 0xFFFF;
     for (unsigned int i = 0; i < data_len; ++i) {
-        uint16_t dbyte = data[i];
+        uint16_t dbyte = __get_far_u8__(data + i, seg);
         crc ^= dbyte << 8;
         for (unsigned char j = 0; j < 8; ++j) {
             uint16_t mix = crc & 0x8000;
@@ -19,15 +19,13 @@ uint16_t crc16(int data_len) {
     return crc;
 }
 
-asm(".global main      \n"
+int main(int argc, int argv[]) {
-    "main:             \n"
+    if (argc < 2) {
-    "  push %bp        \n"
+        return -1;
-    "  mov %sp, %bp    \n"
+    }
-    "  mov 8(%bp), %si \n"
+    uint16_t seg = kDefaultSegment;
-    "  push (%si)      \n"
+    if (argc > 2) {
-    "  call crc16      \n"
+        seg = argv[2];
-    "  add $0x2, %sp   \n"
+    }
-    "  mov 6(%bp), %di \n"
+    return crc16(argv[0], seg, argv[1]);
-    "  mov %ax, (%di)  \n"
+}
-    "  pop %bp         \n"
-    "  lret $4         \n");

src/polmon.cc

@@ -164,15 +164,17 @@ char toupper(char c) {
     return c;
 }
 
-void tofatname(const char* name, char* fatname) {
+void tofatname(const char* name, uint8_t len, char* fatname) {
+    int j = 0;
     for (int i = 0; i < 11; i++) {
-        if (*name == 0 || *name == '.') {
+        if (j == len || name[j] == '.') {
             fatname[i] = ' ';
         } else {
-            fatname[i] = toupper(*name++);
+            fatname[i] = toupper(name[j]);
+            j++;
         }
-        if (i == 7 && *name == '.') {
+        if (i == 7 && name[j] == '.') {
-            name++;
+            j++;
         }
     }
 }
@@ -192,7 +194,8 @@ uint16_t __readfile__(const char* name, uint16_t addr) {
     return ret;
 }
 
-uint16_t LaunchFile(const char* name, uint8_t argc, uint16_t* argv) {
+uint16_t LaunchFile(const char* name, uint8_t len, uint8_t argc,
+                    uint16_t* argv) {
     constexpr uint16_t kSegment = 0x200;
     constexpr uint16_t kAddress = 0x100;
     constexpr uint16_t kHeaderAddress = (kSegment << 4);
@@ -205,9 +208,13 @@ uint16_t LaunchFile(const char* name, uint8_t argc, uint16_t* argv) {
     constexpr uint8_t kTrampoline[] = {0xe8, 0xfd, 0x00, 0xcb};
 
     char fatname[11];
-    tofatname(name, fatname);
+    tofatname(name, len, fatname);
 
     uint16_t r = __readfile__(fatname, kFlatAddress);
+    if (r) {
+        memcpy(fatname + 8, "COM", 3);
+        r = __readfile__(fatname, kFlatAddress);
+    }
     if (r) {
         return r;
     }
@@ -312,7 +319,8 @@ bool ParseCommand(const char* buf, uint16_t& cur_addr, uint16_t& cur_seg) {
                 ptr++;
             }
             const char* fname = ptr;
-            for (; *ptr && *ptr != ' '; ptr++) {
+            int l;
+            for (l = 0; *ptr && *ptr != ' '; l++, ptr++) {
             }
             for (; *ptr && nargs < 8;) {
                 if (*ptr == ' ') {
@@ -321,7 +329,7 @@ bool ParseCommand(const char* buf, uint16_t& cur_addr, uint16_t& cur_seg) {
                 }
                 args[nargs++] = ReadUint16(ptr);
             }
-            uint16_t ret = LaunchFile(fname, nargs, args);
+            uint16_t ret = LaunchFile(fname, l, nargs, args);
             WriteUint16ln(ret);
         } else if (*ptr == 'w') {
             dump = false;

src/polos.h

@@ -1,7 +1,20 @@
 #pragma once
 
+#include <stdint.h>
+
 #define kLpt1 0x10
 #define kUntilIdle 1
 #define kOnce 0
 
 int runcomms(char until_idle);
+
+inline static uint8_t __get_far_u8__(uint16_t addr, uint16_t seg) {
+    register uint16_t ad asm("di") = addr;
+    register uint8_t ret asm("al");
+    asm("mov %2, %%es              \t\n"
+        "movb %%es:(%%di), %%al    \t\n"
+        : "=r"(ret)
+        : "r"(ad), "r"(seg)
+        : "es");
+    return ret;
+}