Refactor parallel comms a bit

polio-main.c

@@ -1,4 +1,6 @@
 #include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
 
 #include "fat12.h"
 #include "paracomm.h"
@@ -11,21 +13,18 @@
 #define kParallelStatusPort 0x3bd
 #define kParallelControlPort 0x3be
 #define kParaDelay 400
+#define kRecvBufferSize 256
 
 void dosdbt();
 void int80h();
 
-uint8_t* parabuf;
+uint8_t parabuf[kRecvBufferSize];
 uint8_t parasize;
 
 static void paracb(const uint8_t* buf, uint8_t size) {
-    if (size > parasize) {
-        return paracb(buf, parasize);
-    }
-    for (int i = 0; i < size; i++) {
-        parabuf[i] = buf[i];
-    }
-    parasize = 0;
+    // we'll mercilessly erase old data with new data
+    memcpy(parabuf, buf, size);
+    parasize = size;
 }
 
 static void die() {
@@ -52,7 +51,7 @@ static void __delay__(int n) {
     }
 }
 
-static void paraxfer() {
+uint8_t xferpara() {
     uint8_t mosib = paracomm_nextbyte();
     __outb__(kParallelDataPort, mosib);
     __outb__(kParallelControlPort, 1);
@@ -61,30 +60,23 @@ static void paraxfer() {
     __delay__(kParaDelay);
     uint8_t mison = __inb__(kParallelStatusPort) >> 4;
     paracomm_feed(mison);
+
+    return paracomm_busy();
 }
 
-void pararecv(uint8_t* addr, uint8_t size) {
-    parabuf = addr;
-    parasize = size;
-    for (int i = 0; i < 1 + 2 + size * 2; i++) {
-        if (!parasize) {
+uint8_t parasend(uint8_t* addr, uint8_t size) {
+    uint8_t i;
+    for (i = 0; i < size; i++) {
+        if (paracomm_send(addr[i])) {
             break;
         }
-        paraxfer();
-    }
-}
-
-void parasend(uint8_t* addr, uint8_t size) {
-    for (int i = 0; i < size; i++) {
-        paracomm_send(addr[i]);
-    }
-    for (int i = 0; i < size + 2; i++) {
-        paraxfer();
     }
+    return i;
 }
 
 int main() {
     dosdbt();
+    parasize = 0;
     paracomm_init(paracb);
 
     fat12_init(kFatAddr, kRootDirAddr);