fweep: make the framepointer a real pointer

Saves us a chunk of RAM

diff --git a/Applications/games/fweep.c b/Applications/games/fweep.c
index c8a4db5..2b78f27 100644 (file)
--- a/Applications/games/fweep.c
+++ b/Applications/games/fweep.c
@@ -99,9 +99,9 @@ uint32_t program_counter;     /* Can be in high memory */
 #define STACKSIZE 256
 #define FRAMESIZE 32
 StackFrame frames[FRAMESIZE];
-int framemax;
+StackFrame *framemax;
 uint16_t stack[STACKSIZE];
-int frameptr;
+StackFrame *frameptr;
 int stackptr;
 int stackmax;
 uint16_t stream3addr[16];
@@ -748,7 +748,7 @@ uint16_t fetch(uint8_t var)
        if (var & 0xF0) {
                return read16low(global_table + ((var - 16) << 1));
        } else if (var) {
-               return stack[frames[frameptr].start + var - 1];
+               return stack[frameptr->start + var - 1];
        } else {
                return stack[--stackptr];
        }
@@ -768,7 +768,7 @@ void store(uint8_t var, uint16_t value)
        if (var & 0xF0) {
                write16(global_table + ((var - 16) << 1), value);
        } else if (var) {
-               stack[frames[frameptr].start + var - 1] = value;
+               stack[frameptr->start + var - 1] = value;
        } else {
                pushstack(value);
        }
@@ -781,20 +781,17 @@ void storei(uint16_t value)
 
 void enter_routine(uint32_t address, boolean stored, int argc)
 {
-       /* FIXME: eventually frameptr sould be a pointer */
-       StackFrame *fp = frames + frameptr;
        int c = read8(address);
        int i;
-       if (frameptr == FRAMESIZE - 1)
+       if (frameptr == &frames[FRAMESIZE - 1])
                panic("out of frames.\n");
 
        /* FIXME: use pointers */
-       fp->pc = program_counter;
-       fp++;
+       frameptr->pc = program_counter;
        frameptr++;
-       fp->argc = argc;
-       fp->start = stackptr;
-       fp->stored = stored;
+       frameptr->argc = argc;
+       frameptr->start = stackptr;
+       frameptr->stored = stored;
        program_counter = address + 1;
        if (frameptr > framemax)
                framemax = frameptr;
@@ -811,15 +808,15 @@ void enter_routine(uint32_t address, boolean stored, int argc)
        if (argc > c)
                argc = c;
        for (i = 0; i < argc; i++)
-               stack[fp->start + i] = inst_args[i + 1];
+               stack[frameptr->start + i] = inst_args[i + 1];
 }
 
 void exit_routine(uint16_t result)
 {
        /* FIXME: we want a live ptr to top frame */
-       stackptr = frames[frameptr].start;
-       program_counter = frames[--frameptr].pc;
-       if (frames[frameptr + 1].stored)
+       stackptr = frameptr->start;
+       program_counter = (--frameptr)->pc;
+       if (frameptr[1].stored)
                store(read8(program_counter - 1), result);
 }
 
@@ -1176,7 +1173,8 @@ uint8_t char_input(void)
 
 void game_restart(void)
 {
-       stackptr = frameptr = 0;
+       stackptr = 0;
+       frameptr = frames;
        program_counter = restart_address;
        paging_restart();
 }
@@ -1219,10 +1217,10 @@ void game_save(uint8_t storage)
        /* Fweep has a nice endian safe blah blah de blah byte by byte
           Save/Restore. We don't bother. Saved games are platfor specific
           Deal with it! */
-       frames[frameptr].pc = program_counter;
-       frames[frameptr + 1].start = stackptr;
+       frameptr->pc = program_counter;
+       frameptr[1].start = stackptr;
        
-       xwrite(f, frames, frameptr + 1, sizeof(StackFrame));
+       xwrite(f, frames, frameptr - frames + 1, sizeof(StackFrame));
        xwrite(f, stack, stackptr, 2);
 
        xwriteb(f, 0xAA);
@@ -1264,7 +1262,7 @@ bad:
 void game_restore(void)
 {
        char filename[64];
-       int f;
+       int f, n;
        uint8_t d;
        uint16_t o, c;
        writes("\n*** Restore? ");
@@ -1280,10 +1278,10 @@ void game_restore(void)
        f = xopen(filename, O_RDONLY, 0600);
        if (f == -1)
                return;
-       frameptr = xread(f, frames, FRAMESIZE, sizeof(StackFrame));
-       if (frameptr == -1)
+       n = xread(f, frames, FRAMESIZE, sizeof(StackFrame));
+       if (n == -1)
                goto bad;
-       frameptr--;
+       frameptr = frames + n - 1;
        stackptr = xread(f, stack, STACKSIZE, 2);
        
        if (xreadb(f) != 0xAA)
@@ -1312,7 +1310,7 @@ void game_restore(void)
 
        while (o < static_start)
                write8(o++, xreadb(story));
-       program_counter = frames[frameptr].pc;
+       program_counter = frameptr->pc;
        return;
        
 bad:
@@ -1501,7 +1499,7 @@ void execute_instruction(void)
                        storei(stackptr - 1);
 
                else
-                       storei(frames[frameptr].start + *inst_args - 1);
+                       storei(frameptr->start + *inst_args - 1);
                break;
        case 0x0D:              // Read through stack/locals reference
                storei(stack[*inst_args]);
@@ -1629,7 +1627,7 @@ void execute_instruction(void)
                break;
        case 0xB9:              // Discard from stack // Catch
                if (VERSION > 4)
-                       storei(frameptr);
+                       storei(frameptr - frames);
 
                else
                        stackptr--;
@@ -1785,7 +1783,7 @@ void execute_instruction(void)
                //NOP
                break;
        case 0xDC:              // Throw
-               frameptr = inst_args[1];
+               frameptr = frames + inst_args[1];
                exit_routine(*inst_args);
                break;
        case 0xDD:              // Bitwise XOR
@@ -2025,7 +2023,7 @@ void execute_instruction(void)
                // (I assume the skip is signed, since many other things are, and +32768 isn't useful anyways.)
                break;
        case 0xFF:              // Check argument count
-               branch(frames[frameptr].argc >= *inst_args);
+               branch(frameptr->argc >= *inst_args);
                break;
 
 #endif                         /*  */