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giant refactoring of macros
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Perry Kivolowitz
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5 changed files with 211 additions and 113 deletions
140
macros/README.md
140
macros/README.md
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@ -25,15 +25,26 @@ underscores to labels defined by libraries such as the CRT and certain
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other symbols like `main`.
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So, `main` will not be found by the linker on Apple systems and `_main`
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will be an error on Linux systems. There are macros to adjust for this.
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will be an error on Linux systems.
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There are some exceptions such as making use of `FILE * stdin`. On
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Linux this would be `stdin`. On Mac OS you would expect `_stdin` but
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you'd be wrong... instead Apple uses `___stdinp`. Why? Apple.
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The macros adjust for this.
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There are some exceptions to the prepending rule on Apple such as making
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use of `FILE * stdin`. On Linux this would be `stdin`. On Mac OS you
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would expect `_stdin` but you'd be wrong... instead Apple uses
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`___stdinp`. Why? Because Apple.
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There is an assumption here that labels created by you do not have
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prepended underscores. This can be a problem if this isn't the case. The
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solution may be to add a parallel set of macros that either do prepend
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or do not. This is an open question which we hope to get user input to
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resolve.
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## Macros of general use
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These macros don't converge Apple and Linux. They're just nice to have.
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First, we describe a number of macros which are the same on both Apple
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and Linux. These macros don't converge Apple and Linux. They're just
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nice to have.
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### PUSH_P, PUSH_R, POP_P and POP_R
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@ -61,97 +72,114 @@ These resolve to: `.cfi_startproc` and `.cfi_endproc` respectively.
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Handy more readable macros for determining minima and maxima.
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`MIN x0, x1, x2`
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Signature:
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resolves to:
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`MIN src_a, src_b, dest`
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`csel x2, x0, x1, GT` putting the minimum of `x0` and `x1` into `x2`.
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The smaller of `src_a` and `src_b` is put into `dest`.
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Signature:
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`MAX src_a, src_b, dest`
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The larger of `src_a` and `src_b` is put into `dest`.
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## Loads and Stores
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### GLD_PTR
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Loads the address of a label and then dereferences it where, on Apple
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Loads the address of a label and then *dereferences* it where, on Apple
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the label is in the global space and on Linux is a relatively close
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label.
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Apple version:
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Signature:
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```text
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.macro GLD_PTR xreg, label // Dereference a global *
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adrp \xreg, _\label@GOTPAGE
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ldr \xreg, [\xreg, _\label@GOTPAGEOFF]
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.endm
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GLD_PTR xreg, label
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```
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Linux version:
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When this macro finishes, the specified x register contains what
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64 bit value lives at the specified label.
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### GLD_ADDR
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Loads the address of the label into the specified x register. No
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dereferencing takes place. On Apple machines, the label will be
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found in the global space.
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Signature:
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```text
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.macro GLD_PTR xreg, label // Dereference a global *
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ldr \xreg, =\label
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ldr \xreg, [\xreg]
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.endm
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GLD_ADDR xreg, label
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```
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When this macro completes, the address of the label is in the x
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register.
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### LLD_ADDR
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Load the value of a "local" label.
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Similar to `GLD_ADDR` this macro loads the address of a "local" label.
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Apple version:
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Signature:
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```text
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.macro LLD_ADDR xreg, label // Load a local address
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adrp \xreg, \label@PAGE
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add \xreg, \xreg, \label@PAGEOFF
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.endm
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LLD_ADDR xreg, label
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```
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Linux version:
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When this macro completes, the address of the label is in the x
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register.
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```text
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.macro LLD_ADDR xreg, label
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ldr \xreg, =\label
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.endm
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```
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### LLD_DBL
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## Extern a global label
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Signature:
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`LLD_DBL xreg, dreg, label`
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When this macro completes, a double that lives at the specified local
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label will sit in the specified double register.
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Note: No underscore is prepended.
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See [this sample program](./double.S) for an example.
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### LLD_FLT
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Signature:
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`LLD_FLT xreg, sreg, label`
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When this macro completes, a float that lives at the specified
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local label will sit in the specified single precision
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register.
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Note: No underscore is prepended.
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See [this sample program](./float.S) for an example.
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## Mark a label as global
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Makes a label available externally.
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Apple version:
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Signature:
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```text
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.macro GLABEL label
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.global _\label
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.endm
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```
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`GLABEL label`
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Linux version:
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An underscore is prepended.
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```text
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.macro GLABEL label
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.global \label
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.endm
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```
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For example:
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```text
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GLABEL main
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```
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## Calling functions
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## Calling CRT functions
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If you create your own function without an underscore, just call it as
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usual.
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If you need to call a function such as those found in the C runtime
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library, use in this way:
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library, use this macro in this way:
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```text
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CRT strlen
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```
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`CRT strlen`
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An underscore is prepended.
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## Declaring `main()`
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Put `MAIN` on a line by itself. Notice there is no colon.
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An underscore is prepended.
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Binary file not shown.
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@ -1,77 +1,87 @@
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// Macros to permit the "same" assembly language to build on ARM64
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// Linux systems as well as Apple Silicon systems.
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//
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// Perry Kivolowitz
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// A Gentle Introduction to Assembly Language
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/* Macros to permit the "same" assembly language to build on ARM64
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Linux systems as well as Apple Silicon systems.
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See the fuller documentation at:
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https://github.com/pkivolowitz/asm_book/blob/main/macros/README.md
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Perry Kivolowitz
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A Gentle Introduction to Assembly Language
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*/
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.macro GLD_PTR xreg, label
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#if defined(__APPLE__)
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// Apple makes a distinction between loading something close by
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// versus something global. Note the use of GOTPAGE rather then
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// PAGE.
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//
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// Note: this macro dereferences the label getting what is at
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// the label's address.
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.macro GLD_PTR xreg, label // Dereference a global *
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adrp \xreg, _\label@GOTPAGE
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ldr \xreg, [\xreg, _\label@GOTPAGEOFF]
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#else
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ldr \xreg, =\label
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ldr \xreg, [\xreg]
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#endif
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.endm
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.macro GLD_ADDR xreg, label // Get a global address
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#if defined(__APPLE__)
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adrp \xreg, _\label@GOTPAGE
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add \xreg, \xreg, _\label@GOTPAGEOFF
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.endm
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// This macro loads the address of a nearby label.
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.macro LLD_ADDR xreg, label // Load a local address
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adrp \xreg, \label@PAGE
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add \xreg, \xreg, \label@PAGEOFF
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.endm
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.macro GLABEL label
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.global _\label
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.endm
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.macro MAIN
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_main:
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.endm
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.macro CRT label
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bl _\label
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.endm
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#else // LINUX
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.macro GLABEL label
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.global \label
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.endm
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.macro MAIN
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main:
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.endm
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.macro CRT label
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bl \label
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.endm
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// This macro treats label as a pointer and dereferences it.
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// That is, it puts into the xreg what is found at the address
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// of the label.
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.macro GLD_PTR xreg, label // Dereference a global *
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#else
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ldr \xreg, =\label
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ldr \xreg, [\xreg]
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#endif
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.endm
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// This macro loads the address of a nearby label.
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.macro LLD_ADDR xreg, label
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#if defined(__APPLE__)
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adrp \xreg, \label@PAGE
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add \xreg, \xreg, \label@PAGEOFF
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#else
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ldr \xreg, =\label
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#endif
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.endm
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.macro LLD_DBL xreg, dreg, label
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#if defined(__APPLE__)
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adrp \xreg, \label@PAGE
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add \xreg, \xreg, \label@PAGEOFF
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ldur \dreg, [\xreg]
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// fmov \dreg, \xreg
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#else
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ldr \xreg, =\label
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ldur \dreg, [\xreg]
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#endif
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.endm
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.macro LLD_FLT xreg, sreg, label
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#if defined(__APPLE__)
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adrp \xreg, \label@PAGE
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add \xreg, \xreg, \label@PAGEOFF
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ldur \sreg, [\xreg]
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#else
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ldr \xreg, =\label
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ldur \sreg, [\xreg]
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#endif
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.endm
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.macro GLABEL label
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#if defined(__APPLE__)
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.global _\label
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#else
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.global \label
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#endif
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.endm
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.macro MAIN
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#if defined(__APPLE__)
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_main:
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#else
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main:
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#endif
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.endm
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.macro CRT label
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#if defined(__APPLE__)
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bl _\label
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#else
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bl \label
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#endif
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.endm
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.macro START_PROC // after starting label
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.cfi_startproc
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29
macros/double.S
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29
macros/double.S
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@ -0,0 +1,29 @@
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#include "apple-linux-convergence.S"
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.text
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.align 2
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GLABEL main
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MAIN
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START_PROC
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PUSH_P x29, x30
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mov x29, sp
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LLD_ADDR x0, fmt
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LLD_DBL x1, d0, dbl
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#if defined(__APPLE__)
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PUSH_R d0
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CRT printf
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add sp, sp, 16
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#else
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CRT printf
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#endif
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POP_P x29, x30
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mov w0, wzr
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ret
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END_PROC
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dbl: .double -0.55
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flt: .float 0.125
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fmt: .asciz "%f\n"
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.end
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31
macros/float.S
Normal file
31
macros/float.S
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@ -0,0 +1,31 @@
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#include "apple-linux-convergence.S"
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.text
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.align 2
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GLABEL main
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MAIN
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START_PROC
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PUSH_P x29, x30
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mov x29, sp
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LLD_ADDR x0, fmt
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LLD_FLT x1, s0, flt
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#if defined(__APPLE__)
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fcvt d0, s0
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fmov x1, d0
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PUSH_R x1
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CRT printf
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add sp, sp, 16
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#else
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fcvt d0, s0
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CRT printf
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#endif
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POP_P x29, x30
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mov w0, wzr
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ret
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END_PROC
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flt: .float 0.125
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fmt: .asciz "%f\n"
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.end
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