/* classes: h_files */ #ifndef SCM_DYNSTACK_H #define SCM_DYNSTACK_H /* Copyright (C) 2012, 2013 Free Software Foundation, Inc. * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public License * as published by the Free Software Foundation; either version 3 of * the License, or (at your option) any later version. * * This library 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 * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA * 02110-1301 USA */ #include "libguile/__scm.h" typedef struct { scm_t_bits *base; scm_t_bits *top; scm_t_bits *limit; } scm_t_dynstack; /* Items on the dynstack are preceded by two-word headers, giving the offset of the preceding item (or 0 if there is none) and the type, flags, and length of the following dynstack entry, in words. In addition, there is a "null header" at the top of the stack, indicating the length of the previous item, but with a tag of zero. For example, consider an empty dynstack, with a capacity of 6 words: +----------+----------+ + |prev=0 |tag=0 | | +----------+----------+ + ^base ^top limit^ Now we evaluate (dynamic-wind enter thunk leave). That will result in a dynstack of: / the len=2 words \ +----------+----------+----------+----------+----------+----------+ |prev=0 |tag:len=2 |enter |leave |prev=4 |tag=0 | +----------+----------+----------+----------+----------+----------+ ^base top,limit^ The tag is a combination of the type of the dynstack item, some flags associated with the item, and the length of the item. See SCM_MAKE_DYNSTACK_TAG below for the details. This arrangement makes it possible to have variable-length dynstack items, and yet be able to traverse them forwards or backwards. */ #define SCM_DYNSTACK_HEADER_LEN 2 #define SCM_DYNSTACK_PREV_OFFSET(top) ((top)[-2]) #define SCM_DYNSTACK_SET_PREV_OFFSET(top, offset) (top)[-2] = (offset) #define SCM_DYNSTACK_TAG(top) ((top)[-1]) #define SCM_DYNSTACK_SET_TAG(top, tag) (top)[-1] = (tag) typedef enum { SCM_DYNSTACK_TYPE_NONE = 0, SCM_DYNSTACK_TYPE_FRAME, SCM_DYNSTACK_TYPE_UNWINDER, SCM_DYNSTACK_TYPE_REWINDER, SCM_DYNSTACK_TYPE_WITH_FLUID, SCM_DYNSTACK_TYPE_PROMPT, SCM_DYNSTACK_TYPE_DYNWIND, SCM_DYNSTACK_TYPE_DYNAMIC_STATE, } scm_t_dynstack_item_type; #define SCM_DYNSTACK_TAG_TYPE_MASK 0xf #define SCM_DYNSTACK_TAG_FLAGS_MASK 0xf0 #define SCM_DYNSTACK_TAG_FLAGS_SHIFT 4 #define SCM_DYNSTACK_TAG_LEN_SHIFT 8 #define SCM_MAKE_DYNSTACK_TAG(type, flags, len) \ ((type) | (flags) | ((len) << SCM_DYNSTACK_TAG_LEN_SHIFT)) #define SCM_DYNSTACK_TAG_TYPE(tag) \ ((tag) & SCM_DYNSTACK_TAG_TYPE_MASK) #define SCM_DYNSTACK_TAG_FLAGS(tag) \ ((tag) & SCM_DYNSTACK_TAG_FLAGS_MASK) #define SCM_DYNSTACK_TAG_LEN(tag) \ ((tag) >> SCM_DYNSTACK_TAG_LEN_SHIFT) #define SCM_DYNSTACK_PREV(top) \ (SCM_DYNSTACK_PREV_OFFSET (top) \ ? ((top) - SCM_DYNSTACK_PREV_OFFSET (top)) : NULL) #define SCM_DYNSTACK_NEXT(top) \ (SCM_DYNSTACK_TAG (top) \ ? ((top) + SCM_DYNSTACK_TAG_LEN (SCM_DYNSTACK_TAG (top)) \ + SCM_DYNSTACK_HEADER_LEN) \ : NULL) #define SCM_DYNSTACK_FIRST(dynstack) \ ((dynstack)->base + SCM_DYNSTACK_HEADER_LEN) #define SCM_DYNSTACK_CAPACITY(dynstack) \ ((dynstack)->limit - (dynstack)->base) #define SCM_DYNSTACK_SPACE(dynstack) \ ((dynstack)->limit - (dynstack)->top) #define SCM_DYNSTACK_HEIGHT(dynstack) \ ((dynstack)->top - (dynstack)->base) #define SCM_DYNSTACK_HAS_SPACE(dynstack, n) \ (SCM_DYNSTACK_SPACE (dynstack) >= n + SCM_DYNSTACK_HEADER_LEN) typedef enum { SCM_F_DYNSTACK_FRAME_REWINDABLE = (1 << SCM_DYNSTACK_TAG_FLAGS_SHIFT) } scm_t_dynstack_frame_flags; typedef enum { SCM_F_DYNSTACK_WINDER_EXPLICIT = (1 << SCM_DYNSTACK_TAG_FLAGS_SHIFT) } scm_t_dynstack_winder_flags; typedef enum { SCM_F_DYNSTACK_PROMPT_ESCAPE_ONLY = (1 << SCM_DYNSTACK_TAG_FLAGS_SHIFT) } scm_t_dynstack_prompt_flags; typedef void (*scm_t_guard) (void *); /* Pushing and popping entries on the dynamic stack. */ SCM_INTERNAL void scm_dynstack_push_frame (scm_t_dynstack *, scm_t_dynstack_frame_flags); SCM_INTERNAL void scm_dynstack_push_rewinder (scm_t_dynstack *, scm_t_dynstack_winder_flags, scm_t_guard, void *); SCM_INTERNAL void scm_dynstack_push_unwinder (scm_t_dynstack *, scm_t_dynstack_winder_flags, scm_t_guard, void *); SCM_INTERNAL void scm_dynstack_push_fluid ( scm_t_dynstack *, SCM fluid, SCM value, scm_t_dynamic_state *dynamic_state); SCM_INTERNAL void scm_dynstack_push_dynamic_state (scm_t_dynstack *, SCM, scm_t_dynamic_state *); SCM_INTERNAL void scm_dynstack_push_prompt (scm_t_dynstack *, scm_t_dynstack_prompt_flags, SCM key, scm_t_ptrdiff fp_offset, scm_t_ptrdiff sp_offset, scm_t_uint32 *ip, scm_i_jmp_buf *registers); SCM_INTERNAL void scm_dynstack_push_dynwind (scm_t_dynstack *, SCM enter, SCM leave); SCM_INTERNAL void scm_dynstack_pop (scm_t_dynstack *); /* Capturing, winding, and unwinding. */ SCM_INTERNAL scm_t_dynstack* scm_dynstack_capture_all (scm_t_dynstack *dynstack); SCM_INTERNAL scm_t_dynstack* scm_dynstack_capture (scm_t_dynstack *dynstack, scm_t_bits *item); SCM_INTERNAL void scm_dynstack_wind_1 (scm_t_dynstack *, scm_t_bits *); SCM_INTERNAL scm_t_bits scm_dynstack_unwind_1 (scm_t_dynstack *); SCM_INTERNAL void scm_dynstack_wind (scm_t_dynstack *, scm_t_bits *); SCM_INTERNAL void scm_dynstack_unwind (scm_t_dynstack *, scm_t_bits *); /* Miscellany. */ SCM_INTERNAL scm_t_bits* scm_dynstack_unwind_fork (scm_t_dynstack *, scm_t_dynstack *); SCM_INTERNAL void scm_dynstack_unwind_frame (scm_t_dynstack *); SCM_INTERNAL void scm_dynstack_unwind_fluid (scm_t_dynstack *dynstack, scm_t_dynamic_state *dynamic_state); SCM_INTERNAL void scm_dynstack_unwind_dynamic_state (scm_t_dynstack *dynstack, scm_t_dynamic_state *dynamic_state); SCM_INTERNAL scm_t_bits* scm_dynstack_find_prompt (scm_t_dynstack *, SCM, scm_t_dynstack_prompt_flags *, scm_t_ptrdiff *, scm_t_ptrdiff *, scm_t_uint32 **, scm_i_jmp_buf **); SCM_INTERNAL SCM scm_dynstack_find_old_fluid_value (scm_t_dynstack *, SCM, size_t, SCM); SCM_INTERNAL void scm_dynstack_relocate_prompts (scm_t_dynstack *, scm_t_ptrdiff); SCM_INTERNAL void scm_dynstack_wind_prompt (scm_t_dynstack *, scm_t_bits *, scm_t_ptrdiff, scm_i_jmp_buf *); #endif /* SCM_DYNSTACK_H */ /* Local Variables: c-file-style: "gnu" End: */