From 7d0826b57bc01bc0968ac933e81e74baab1cb318 Mon Sep 17 00:00:00 2001
From: jacob <jacob@cagori.com>
Date: Thu, 30 Jan 2025 11:38:35 -0600
Subject: [PATCH] give byte writer option to be backed by an arena

---
 src/ase.c    |  4 +--
 src/byteio.c | 82 +++++++++++++++++++++++++++++++++++-----------------
 src/byteio.h | 70 ++++++++++++++++----------------------------
 src/tar.c    |  2 +-
 src/user.c   |  5 ++--
 5 files changed, 87 insertions(+), 76 deletions(-)

diff --git a/src/ase.c b/src/ase.c
index 36c7caaa..7a425165 100644
--- a/src/ase.c
+++ b/src/ase.c
@@ -558,7 +558,7 @@ struct ase_decode_image_result ase_decode_image(struct arena *arena, struct buff
     struct temp_arena scratch = scratch_begin(arena);
     struct ase_decode_image_result res = ZI;
 
-    struct byte_reader br = br_create_from_buffer(encoded);
+    struct byte_reader br = br_from_buffer(encoded);
     struct ase_header ase_header;
     br_read_to_struct(&br, &ase_header);
 
@@ -817,7 +817,7 @@ struct ase_decode_sheet_result ase_decode_sheet(struct arena *arena, struct buff
 
     struct ase_decode_sheet_result res = ZI;
 
-    struct byte_reader br = br_create_from_buffer(encoded);
+    struct byte_reader br = br_from_buffer(encoded);
     struct ase_header ase_header;
     br_read_to_struct(&br, &ase_header);
 
diff --git a/src/byteio.c b/src/byteio.c
index d990ecc1..9b50d4b6 100644
--- a/src/byteio.c
+++ b/src/byteio.c
@@ -1,13 +1,47 @@
 #include "byteio.h"
 #include "memory.h"
+#include "arena.h"
 
 /* ========================== *
  * Writer
  * ========================== */
 
+INTERNAL b32 write_check_overflow(struct byte_writer *bw, u64 amount)
+{
+    b32 overflowed = bw->overflowed;
+    i64 new_space_left = (bw->at + amount) - (bw->buff.data + bw->buff.size);
+    if (!overflowed && new_space_left < 0) {
+        if (bw->arena) {
+            arena_push_array(bw->arena, u8, -new_space_left);
+            bw->buff.size += -new_space_left;
+            /* Writer memory should be contiguous in arena */
+            ASSERT((bw->buff.data + bw->buff.size) == (bw->arena->base + bw->arena->pos));
+        } else {
+            bw->overflowed = true;
+            overflowed = true;
+        }
+    }
+    ASSERT(!overflowed);
+    return overflowed;
+}
+
+INTERNAL void write_unsafe(struct byte_writer *bw, void *v, u64 size)
+{
+    MEMCPY(bw->at, v, size);
+    bw->at += size;
+}
+
+INTERNAL void write(struct byte_writer *bw, void *v, u64 size)
+{
+    if (write_check_overflow(bw, sizeof(v))) {
+        return;
+    }
+    write_unsafe(bw, v, size);
+}
+
 void bw_seek(struct byte_writer *bw, u64 amount)
 {
-    if (bw_overflow_check(bw, amount)) {
+    if (write_check_overflow(bw, amount)) {
         return;
     }
     bw->at += amount;
@@ -22,20 +56,6 @@ void bw_seek_to(struct byte_writer *bw, u64 pos)
     bw->at = bw->buff.data + pos;
 }
 
-INTERNAL void write_unsafe(struct byte_writer *bw, void *v, u64 size)
-{
-    MEMCPY(bw->at, v, size);
-    bw->at += size;
-}
-
-INTERNAL void write(struct byte_writer *bw, void *v, u64 size)
-{
-    if (bw_overflow_check(bw, sizeof(v))) {
-        return;
-    }
-    write_unsafe(bw, v, size);
-}
-
 void bw_write_buffer(struct byte_writer *bw, struct buffer buff)
 {
     write(bw, buff.data, buff.size);
@@ -97,9 +117,19 @@ void bw_write_var_sint(struct byte_writer *bw, i64 v)
  * Reader
  * ========================== */
 
+INTERNAL b32 read_check_overflow(struct byte_reader *br, u64 amount)
+{
+    if (br->overflowed || br->at + amount > br->buff.data + br->buff.size) {
+        ASSERT(false);
+        br->overflowed = true;
+        return true;
+    }
+    return false;
+}
+
 void br_seek(struct byte_reader *br, u64 amount)
 {
-    if (br_overflow_check(br, amount)) {
+    if (read_check_overflow(br, amount)) {
         return;
     }
     br->at += amount;
@@ -124,7 +154,7 @@ INTERNAL void *read_unsafe(struct byte_reader *br, u64 size)
 /* Will return NULL on overflow */
 void *br_read_raw(struct byte_reader *br, u64 size)
 {
-    if (br_overflow_check(br, size)) {
+    if (read_check_overflow(br, size)) {
         return NULL;
     }
     return read_unsafe(br, size);
@@ -133,7 +163,7 @@ void *br_read_raw(struct byte_reader *br, u64 size)
 /* Will not read any data on overflow */
 void br_read_to_buffer(struct byte_reader *br, struct buffer buff)
 {
-    if (br_overflow_check(br, buff.size)) {
+    if (read_check_overflow(br, buff.size)) {
         return;
     }
     u8 *bytes = read_unsafe(br, buff.size);
@@ -142,7 +172,7 @@ void br_read_to_buffer(struct byte_reader *br, struct buffer buff)
 
 u8 br_read_u8(struct byte_reader *br)
 {
-    if (br_overflow_check(br, sizeof(u8))) {
+    if (read_check_overflow(br, sizeof(u8))) {
         return 0;
     }
     u8 res = 0;
@@ -152,7 +182,7 @@ u8 br_read_u8(struct byte_reader *br)
 
 u16 br_read_u16(struct byte_reader *br)
 {
-    if (br_overflow_check(br, sizeof(u16))) {
+    if (read_check_overflow(br, sizeof(u16))) {
         return 0;
     }
     u16 res = 0;
@@ -162,7 +192,7 @@ u16 br_read_u16(struct byte_reader *br)
 
 u32 br_read_u32(struct byte_reader *br)
 {
-    if (br_overflow_check(br, sizeof(u32))) {
+    if (read_check_overflow(br, sizeof(u32))) {
         return 0;
     }
     u32 res = 0;
@@ -172,7 +202,7 @@ u32 br_read_u32(struct byte_reader *br)
 
 u64 br_read_u64(struct byte_reader *br)
 {
-    if (br_overflow_check(br, sizeof(u64))) {
+    if (read_check_overflow(br, sizeof(u64))) {
         return 0;
     }
     u64 res = 0;
@@ -182,7 +212,7 @@ u64 br_read_u64(struct byte_reader *br)
 
 i8 br_read_i8(struct byte_reader *br)
 {
-    if (br_overflow_check(br, sizeof(i8))) {
+    if (read_check_overflow(br, sizeof(i8))) {
         return 0;
     }
     i8 res = 0;
@@ -192,7 +222,7 @@ i8 br_read_i8(struct byte_reader *br)
 
 i16 br_read_i16(struct byte_reader *br)
 {
-    if (br_overflow_check(br, sizeof(i16))) {
+    if (read_check_overflow(br, sizeof(i16))) {
         return 0;
     }
     i16 res = 0;
@@ -202,7 +232,7 @@ i16 br_read_i16(struct byte_reader *br)
 
 i32 br_read_i32(struct byte_reader *br)
 {
-    if (br_overflow_check(br, sizeof(i32))) {
+    if (read_check_overflow(br, sizeof(i32))) {
         return 0;
     }
     i32 res = 0;
@@ -212,7 +242,7 @@ i32 br_read_i32(struct byte_reader *br)
 
 i64 br_read_i64(struct byte_reader *br)
 {
-    if (br_overflow_check(br, sizeof(i64))) {
+    if (read_check_overflow(br, sizeof(i64))) {
         return 0;
     }
     i64 res = 0;
diff --git a/src/byteio.h b/src/byteio.h
index e139b9af..dea6ac81 100644
--- a/src/byteio.h
+++ b/src/byteio.h
@@ -2,6 +2,7 @@
 #define BYTEIO_H
 
 struct byte_writer {
+    struct arena *arena;  /* If arena is set, then the writer cannot overflow and will instead allocate more memory as it grows */
     struct buffer buff;
     b32 overflowed;
     u8 *at;
@@ -17,22 +18,30 @@ struct byte_reader {
  * Constructor utils
  * ========================== */
 
-INLINE struct byte_writer bw_create_from_buffer(struct buffer buff)
+INLINE struct byte_writer bw_from_buffer(struct buffer buff)
 {
-    return (struct byte_writer) {
-        .buff = buff,
-        .overflowed = false,
-        .at = buff.data
-    };
+    struct byte_writer bw = ZI;
+    bw.buff = buff;
+    bw.at = buff.data;
+    return bw;
 }
 
-INLINE struct byte_reader br_create_from_buffer(struct buffer buff)
+INLINE struct byte_writer bw_from_arena(struct arena *arena)
 {
-    return (struct byte_reader) {
-        .buff = buff,
-        .overflowed = false,
-        .at = buff.data
-    };
+    struct byte_writer bw = ZI;
+    bw.arena = arena;
+    bw.buff.data = arena->base;
+    bw.buff.size = 0;
+    bw.at = bw.buff.data;
+    return bw;
+}
+
+INLINE struct byte_reader br_from_buffer(struct buffer buff)
+{
+    struct byte_reader br = ZI;
+    br.buff = buff;
+    br.at = buff.data;
+    return br;
 }
 
 INLINE struct byte_writer bw_copy(struct byte_writer *bw)
@@ -48,10 +57,10 @@ INLINE struct byte_reader br_copy(struct byte_reader *br)
 /* Generate a buffer struct containing written bytes only */
 INLINE struct buffer bw_get_written_buffer(struct byte_writer *bw)
 {
-    return (struct buffer) {
-        .data = bw->buff.data,
-        .size = bw->at - bw->buff.data
-    };
+    struct buffer buff = ZI;
+    buff.data = bw->buff.data;
+    buff.size = bw->at - bw->buff.data;
+    return buff;
 }
 
 INLINE u64 bw_pos(struct byte_reader *bw)
@@ -59,30 +68,6 @@ INLINE u64 bw_pos(struct byte_reader *bw)
     return bw->at - bw->buff.data;
 }
 
-/* ========================== *
- * Overflow utils
- * ========================== */
-
-INLINE b32 bw_overflow_check(struct byte_writer *bw, u64 amount)
-{
-    if (bw->overflowed || bw->at + amount > bw->buff.data + bw->buff.size) {
-        ASSERT(false);
-        bw->overflowed = true;
-        return true;
-    }
-    return false;
-}
-
-INLINE b32 br_overflow_check(struct byte_reader *br, u64 amount)
-{
-    if (br->overflowed || br->at + amount > br->buff.data + br->buff.size) {
-        ASSERT(false);
-        br->overflowed = true;
-        return true;
-    }
-    return false;
-}
-
 /* ========================== *
  * Write
  * ========================== */
@@ -102,11 +87,6 @@ void bw_write_i64(struct byte_writer *bw, i64 v);
 void bw_write_var_uint(struct byte_writer *bw, u64 v);
 void bw_write_var_sint(struct byte_writer *bw, i64 v);
 
-INLINE u64 bw_bytes_left(struct byte_writer *bw)
-{
-    return bw->overflowed ? 0 : bw->buff.size - (bw->at - bw->buff.data);
-}
-
 /* ========================== *
  * Read
  * ========================== */
diff --git a/src/tar.c b/src/tar.c
index 90bc462c..ab99393d 100644
--- a/src/tar.c
+++ b/src/tar.c
@@ -70,7 +70,7 @@ struct tar_archive tar_parse(struct arena *arena, struct buffer data, struct str
     __prof;
 
     struct tar_archive archive = ZI;
-    struct byte_reader br = br_create_from_buffer(data);
+    struct byte_reader br = br_from_buffer(data);
 
     u64 num_files = 0;
     while (br_bytes_left(&br) > 1024) {
diff --git a/src/user.c b/src/user.c
index b51fd6c5..59d353da 100644
--- a/src/user.c
+++ b/src/user.c
@@ -936,7 +936,7 @@ INTERNAL void user_update(void)
 
             b32 skip_debug_draw = !G.debug_camera && ent == active_camera;
             b32 skip_debug_draw_transform = entity_has_prop(ent, ENTITY_PROP_CAMERA);
-            //skip_debug_draw_transform = true;
+            skip_debug_draw_transform = true;
 
             struct xform sprite_xform = xf;
 
@@ -1612,7 +1612,7 @@ INTERNAL void user_update(void)
         struct rect ui_viewport = RECT_FROM_V2(V2(0, 0), G.ui_size);
         struct rect backbuffer_viewport = RECT_FROM_V2(V2(0, 0), G.screen_size);
 
-        /* Allocate rt textures */
+        /* Allocate render textures */
         struct v2i32 ui_resolution = v2_round_to_int(ui_viewport.size);
         struct v2i32 backbuffer_resolution = v2_round_to_int(backbuffer_viewport.size);
         struct v2i32 world_resolution = ui_resolution;
@@ -1645,6 +1645,7 @@ INTERNAL void user_update(void)
             }
         }
 
+        /* Combine render textures w/ quad draw cmds */
         {
             /* Draw world texture to final */
             {