Implementation of Unlambda, an esoteric programming language.
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/*
* vm_stack.c - Unlambda VM segmented stacks
*
* Copyright (C) 2020 CismonX <admin@cismon.net>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#include "vm_stack.h"
#include "vm_pool.h"
#include "logging.h"
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
static inline struct u6a_vm_stack*
vm_stack_create(struct u6a_vm_stack_ctx* ctx, struct u6a_vm_stack* prev, uint32_t top) {
const uint32_t size = sizeof(struct u6a_vm_stack) + ctx->stack_seg_len * sizeof(struct u6a_vm_var_fn);
struct u6a_vm_stack* vs = malloc(size);
if (UNLIKELY(vs == NULL)) {
u6a_err_bad_alloc(ctx->err_stage, size);
return NULL;
}
vs->prev = prev;
vs->top = top;
vs->refcnt = 0;
return vs;
}
static inline struct u6a_vm_stack*
vm_stack_dup(struct u6a_vm_stack_ctx* ctx, struct u6a_vm_stack* vs) {
const uint32_t size = sizeof(struct u6a_vm_stack) + ctx->stack_seg_len * sizeof(struct u6a_vm_var_fn);
struct u6a_vm_stack* dup_stack = malloc(size);
if (UNLIKELY(dup_stack == NULL)) {
u6a_err_bad_alloc(ctx->err_stage, size);
return NULL;
}
memcpy(dup_stack, vs, sizeof(struct u6a_vm_stack) + (vs->top + 1) * sizeof(struct u6a_vm_var_fn));
dup_stack->refcnt = 0;
for (uint32_t idx = vs->top; idx < UINT32_MAX; --idx) {
struct u6a_vm_var_fn elem = vs->elems[idx];
if (elem.token.fn & U6A_VM_FN_REF) {
u6a_vm_pool_addref(ctx->pool_ctx->active_pool, elem.ref);
}
}
if (vs->prev) {
++vs->prev->refcnt;
}
return dup_stack;
}
static inline void
vm_stack_free(struct u6a_vm_stack_ctx* ctx, struct u6a_vm_stack* vs) {
struct u6a_vm_stack* prev;
vs->refcnt = 1;
do {
prev = vs->prev;
if (--vs->refcnt == 0) {
for (uint32_t idx = vs->top; idx < UINT32_MAX; --idx) {
struct u6a_vm_var_fn elem = vs->elems[idx];
if (elem.token.fn & U6A_VM_FN_REF) {
u6a_vm_pool_free(ctx->pool_ctx, elem.ref);
}
}
free(vs);
vs = prev;
} else {
break;
}
} while (vs);
}
bool
u6a_vm_stack_init(struct u6a_vm_stack_ctx* ctx, uint32_t stack_seg_len, const char* err_stage) {
ctx->stack_seg_len = stack_seg_len;
ctx->err_stage = err_stage;
ctx->active_stack = vm_stack_create(ctx, NULL, UINT32_MAX);
return ctx->active_stack != NULL;
}
// Boilerplates below. If only we have C++ templates here... (macros just make things nastier)
U6A_HOT bool
u6a_vm_stack_push1_split_(struct u6a_vm_stack_ctx* ctx, struct u6a_vm_var_fn v0) {
struct u6a_vm_stack* vs = ctx->active_stack;
ctx->active_stack = vm_stack_create(ctx, vs, 0);
if (UNLIKELY(ctx->active_stack == NULL)) {
ctx->active_stack = vs;
return false;
}
++vs->refcnt;
ctx->active_stack->elems[0] = v0;
return true;
}
U6A_HOT bool
u6a_vm_stack_push2_split_(struct u6a_vm_stack_ctx* ctx, struct u6a_vm_var_fn v0, struct u6a_vm_var_fn v1) {
struct u6a_vm_stack* vs = ctx->active_stack;
ctx->active_stack = vm_stack_create(ctx, vs, 1);
if (UNLIKELY(ctx->active_stack == NULL)) {
ctx->active_stack = vs;
return false;
}
++vs->refcnt;
ctx->active_stack->elems[0] = v0;
ctx->active_stack->elems[1] = v1;
return true;
}
U6A_HOT bool
u6a_vm_stack_push3_split_(struct u6a_vm_stack_ctx* ctx, struct u6a_vm_var_fn v0, struct u6a_vm_var_fn v1,
struct u6a_vm_var_fn v2)
{
struct u6a_vm_stack* vs = ctx->active_stack;
ctx->active_stack = vm_stack_create(ctx, vs, 2);
if (UNLIKELY(ctx->active_stack == NULL)) {
ctx->active_stack = vs;
return false;
}
++vs->refcnt;
ctx->active_stack->elems[0] = v0;
ctx->active_stack->elems[1] = v1;
ctx->active_stack->elems[2] = v2;
return true;
}
U6A_HOT bool
u6a_vm_stack_push4_split_(struct u6a_vm_stack_ctx* ctx, struct u6a_vm_var_fn v0, struct u6a_vm_var_fn v1,
struct u6a_vm_var_fn v2, struct u6a_vm_var_fn v3)
{
struct u6a_vm_stack* vs = ctx->active_stack;
ctx->active_stack = vm_stack_create(ctx, vs, 3);
if (UNLIKELY(ctx->active_stack == NULL)) {
ctx->active_stack = vs;
return false;
}
++vs->refcnt;
ctx->active_stack->elems[0] = v0;
ctx->active_stack->elems[1] = v1;
ctx->active_stack->elems[2] = v2;
ctx->active_stack->elems[3] = v3;
return true;
}
U6A_HOT bool
u6a_vm_stack_pop_split_(struct u6a_vm_stack_ctx* ctx) {
struct u6a_vm_stack* vs = ctx->active_stack;
ctx->active_stack = vs->prev;
if (UNLIKELY(ctx->active_stack == NULL)) {
u6a_err_stack_underflow(ctx->err_stage);
ctx->active_stack = vs;
return false;
}
if (--ctx->active_stack->refcnt > 0) {
ctx->active_stack = vm_stack_dup(ctx, ctx->active_stack);
}
if (UNLIKELY(ctx->active_stack == NULL)) {
ctx->active_stack = vs;
return false;
}
free(vs);
--ctx->active_stack->top;
return true;
}
U6A_HOT struct u6a_vm_var_fn
u6a_vm_stack_xch_split_(struct u6a_vm_stack_ctx* ctx, struct u6a_vm_var_fn v0) {
struct u6a_vm_stack* vs = ctx->active_stack;
struct u6a_vm_var_fn elem;
// XCH on segmented stacks is inefficient, perhaps there's a better solution?
struct u6a_vm_stack* prev = vs->prev;
if (UNLIKELY(prev == NULL)) {
u6a_err_stack_underflow(ctx->err_stage);
return U6A_VM_VAR_FN_EMPTY;
}
if (--prev->refcnt > 0) {
prev = vm_stack_dup(ctx, prev);
if (UNLIKELY(prev == NULL)) {
return U6A_VM_VAR_FN_EMPTY;
}
}
if (vs->top == 0) {
++prev->refcnt;
vs->prev = prev;
elem = prev->elems[prev->top];
prev->elems[prev->top] = v0;
} else {
free(vs);
ctx->active_stack = prev;
elem = prev->elems[prev->top - 1];
prev->elems[prev->top - 1] = v0;
}
return elem;
}
struct u6a_vm_stack*
u6a_vm_stack_dup(struct u6a_vm_stack_ctx* ctx, struct u6a_vm_stack* vs) {
return vm_stack_dup(ctx, vs);
}
void
u6a_vm_stack_discard(struct u6a_vm_stack_ctx* ctx, struct u6a_vm_stack* vs) {
vm_stack_free(ctx, vs);
}
void
u6a_vm_stack_destroy(struct u6a_vm_stack_ctx* ctx) {
vm_stack_free(ctx, ctx->active_stack);
}