From 7ec2f90d382ae8593fcdafa9906fb49df02e29fd Mon Sep 17 00:00:00 2001
From: zongor <admin@alfrescocavern.com>
Date: Sat, 5 Jul 2025 23:29:07 -0400
Subject: [PATCH] add function example

---
 src/compiler.c | 32 ++++++++++++++++++++++++++------
 src/debug.c    | 24 ++++++++++++++++++++++++
 src/main.c     |  2 +-
 src/opcodes.h  |  8 ++++----
 src/vm.c       | 27 ++++++++++++++++++++++-----
 5 files changed, 77 insertions(+), 16 deletions(-)

diff --git a/src/compiler.c b/src/compiler.c
index 4c77639..68a4c83 100644
--- a/src/compiler.c
+++ b/src/compiler.c
@@ -44,19 +44,39 @@ uint32_t test_loop_compile(Value *memory) {
 }
 
 uint32_t test_add_function_compile(Value *memory) {
-  uint32_t i = 0;
-  memory[i++].u = OP(OP_POP_ARGS, 0, 0, 0);
-  memory[i++].u = OP(OP_ADD_INT, 2, 1, 0);
+  uint32_t i = 3;
+  memory[i++].u = OP(OP_POPU, 0, 0, 0); /* return ptr */
+  memory[i++].u = OP(OP_POPI, 1, 0, 0); /* a int */
+  memory[i++].u = OP(OP_POPI, 2, 0, 0); /* b int */
+  memory[i++].u = OP(OP_ADD_INT, 3, 2, 1); /* a + b */
+  memory[i++].u = OP(OP_PUSHI, 3, 0, 0); /* return */
   memory[i++].u = OP(OP_RETURN, 0, 0, 0);
+  uint32_t main = i;
+  memory[0].u = OP(OP_LOADF, 0, 0, 0);
+  memory[1].u = main;
+  memory[2].u = OP(OP_JMP, 0, 0, 0); /* jump to 'main' */
+  memory[i++].u = OP(OP_LOADI, 0, 0, 0); /* 1 */
+  memory[i++].i = 1;
+  memory[i++].u = OP(OP_PUSHI, 0, 0, 0);
+  memory[i++].u = OP(OP_LOADI, 0, 0, 0); /* 1 */
+  memory[i++].i = 1;
+  memory[i++].u = OP(OP_PUSHI, 0, 0, 0);
+  uint32_t add_fn_return = i + 6; /* after the call */
+  memory[i++].u = OP(OP_LOADI, 0, 0, 0); /* return */
+  memory[i++].u = add_fn_return;
+  memory[i++].u = OP(OP_PUSHU, 0, 0, 0); 
+  memory[i++].u = OP(OP_LOADU, 0, 0, 0); /* add fn ptr */
+  memory[i++].u = 3;
+  memory[i++].u = OP(OP_CALL, 0, 0, 0); /* ); */
+  memory[i++].u = OP(OP_POPI, 0, 0, 0); /* get return value */
+  memory[i++].u = OP(OP_INT_TO_STRING, 1, 0, 0);
+  memory[i++].u = OP(OP_PRINT_STRING, 0, 1, 0); /* print(sum.toS()); */
   memory[i++].u = OP(OP_HALT, 0, 0, 0);
   return i;
 }
 
 uint32_t test_recursive_function_compile(Value *memory) {
   uint32_t i = 0;
-  memory[i++].u = OP(OP_POP_ARGS, 0, 0, 0);
-  memory[i++].u = OP(OP_ADD_INT, 2, 1, 0);
-  memory[i++].u = OP(OP_RETURN, 0, 0, 0);
   memory[i++].u = OP(OP_HALT, 0, 0, 0);
   return i;
 }
diff --git a/src/debug.c b/src/debug.c
index 693f9b0..778812f 100644
--- a/src/debug.c
+++ b/src/debug.c
@@ -23,6 +23,12 @@ void printOp(uint8_t op, uint8_t dest, uint8_t src1, uint8_t src2) {
   case OP_HALT:
     printf("[HALT] $%d, $%d, $%d\n", dest, src1, src2);
     break;
+  case OP_CALL:
+    printf("[CALL] $%d, $%d, $%d\n", dest, src1, src2);
+    break;
+  case OP_RETURN:
+    printf("[RETURN] $%d, $%d, $%d\n", dest, src1, src2);
+    break;
   case OP_LOADI:
     printf("[LOADI] $%d, $%d, $%d\n", dest, src1, src2);
     break;
@@ -41,6 +47,24 @@ void printOp(uint8_t op, uint8_t dest, uint8_t src1, uint8_t src2) {
   case OP_STOREF:
     printf("[STOREF] $%d, $%d, $%d\n", dest, src1, src2);
     break;
+  case OP_PUSHI:
+    printf("[PUSHI] $%d, $%d, $%d\n", dest, src1, src2);
+    break;
+  case OP_PUSHU:
+    printf("[PUSHU] $%d, $%d, $%d\n", dest, src1, src2);
+    break;
+  case OP_PUSHF:
+    printf("[PUSHF] $%d, $%d, $%d\n", dest, src1, src2);
+    break;
+  case OP_POPI:
+    printf("[POPI] $%d, $%d, $%d\n", dest, src1, src2);
+    break;
+  case OP_POPU:
+    printf("[POPU] $%d, $%d, $%d\n", dest, src1, src2);
+    break;
+  case OP_POPF:
+    printf("[POPF] $%d, $%d, $%d\n", dest, src1, src2);
+    break;
   case OP_ADD_INT:
     printf("[ADD_INT] $%d, $%d, $%d\n", dest, src1, src2);
     break;
diff --git a/src/main.c b/src/main.c
index bad2cfb..7159d44 100644
--- a/src/main.c
+++ b/src/main.c
@@ -54,7 +54,7 @@ int main(int argc, char **argv) {
   vm.frames_size = FRAMES_SIZE;
   vm.stack_size = STACK_SIZE;
   vm.memory_size = MEMORY_SIZE;
-  vm.frames[vm.fp].allocated.end = test_loop_compile(vm.memory);
+  vm.frames[vm.fp].allocated.end = test_add_function_compile(vm.memory);
 
 #ifdef __EMSCRIPTEN__
   emscripten_set_main_loop(mainloop, 0, 1);
diff --git a/src/opcodes.h b/src/opcodes.h
index 4eb6fc9..e5b91f8 100644
--- a/src/opcodes.h
+++ b/src/opcodes.h
@@ -17,7 +17,7 @@ typedef struct {
 
 #define MAX_REGS 256
 typedef struct {
-  Value registers[MAX_REGS]; /* R0-R[MAX_REGS-1] */
+  Value registers[MAX_REGS]; /* R0-R255 */
   uint32_t rp;               /* register pointer (last unused) */
   Slice allocated;           /* start and end of global allocated block */
 } Frame;
@@ -31,11 +31,11 @@ typedef struct {
   uint32_t rp; /* Return stack pointer (top of stack) */
   uint32_t mp; /* Memory pointer (last allocated value) */
   uint32_t frames_size;
-  Frame frames[FRAMES_SIZE];
+  Frame frames[FRAMES_SIZE]; /* function call frames */
   uint32_t stack_size;
-  Value stack[STACK_SIZE];
+  Value stack[STACK_SIZE]; /* main stack */
   uint32_t memory_size;
-  Value memory[MEMORY_SIZE]; /* Memory array */
+  Value memory[MEMORY_SIZE]; /* memory array */
 } VM;
 
 typedef enum {
diff --git a/src/vm.c b/src/vm.c
index f523f3a..7f002e0 100644
--- a/src/vm.c
+++ b/src/vm.c
@@ -54,7 +54,6 @@ bool step_vm(VM *vm) {
   case OP_HALT:
     return false;
   case OP_CALL:
-    vm->stack[++vm->rp].u = vm->pc; /* push return address */
     vm->pc = vm->frames[vm->fp]
                  .registers[dest]
                  .u; /* set pc to location of function in memory */
@@ -85,13 +84,31 @@ bool step_vm(VM *vm) {
     vm->frames[vm->fp].registers[dest].f = vm->memory[vm->pc++].f;
     return true;
   case OP_STOREI:
-    vm->memory[vm->pc++].i = vm->frames[vm->fp].registers[src1].i;
+    vm->memory[vm->pc++].i = vm->frames[vm->fp].registers[dest].i;
     return true;
   case OP_STOREU:
-    vm->memory[vm->pc++].u = vm->frames[vm->fp].registers[src1].u;
+    vm->memory[vm->pc++].u = vm->frames[vm->fp].registers[dest].u;
     return true;
   case OP_STOREF:
-    vm->memory[vm->pc++].f = vm->frames[vm->fp].registers[src1].f;
+    vm->memory[vm->pc++].f = vm->frames[vm->fp].registers[dest].f;
+    return true;
+  case OP_PUSHI:
+    vm->stack[++vm->rp].i = vm->frames[vm->fp].registers[dest].i;
+    return true;
+  case OP_PUSHU:
+    vm->stack[++vm->rp].u = vm->frames[vm->fp].registers[dest].u;
+    return true;
+  case OP_PUSHF:
+    vm->stack[++vm->rp].f = vm->frames[vm->fp].registers[dest].f;
+    return true;
+  case OP_POPI:
+    vm->frames[vm->fp].registers[dest].i = vm->stack[vm->rp--].i;
+    return true;
+  case OP_POPU:
+    vm->frames[vm->fp].registers[dest].u = vm->stack[vm->rp--].u;
+    return true;
+  case OP_POPF:
+    vm->frames[vm->fp].registers[dest].f = vm->stack[vm->rp--].f;
     return true;
   case OP_ADD_INT:
     MATH_OP(i, +);
@@ -137,7 +154,7 @@ bool step_vm(VM *vm) {
     vm->frames[vm->fp].registers[dest] = vm->frames[vm->fp].registers[src1];
     return true;
   case OP_JMP:
-    vm->pc = vm->frames[vm->fp].registers[src1].u; /* Jump to address */
+    vm->pc = vm->frames[vm->fp].registers[dest].u; /* Jump to address */
     return true;
   case OP_JEQ_UINT: {
     COMPARE_AND_JUMP(uint32_t, u, ==);